Biscuit- In America this is a particular class of bread (like buns or rolls) eaten with meals, including breakfast. It is not a pastry, as reported on the web page. It is associated with less formal dining than dinner rolls, but nonetheless may put in an appearance at Thanksgiving.  As such, it is never sweet, except to the extent one puts jam or jelly on it at breakfast.  Usually, people just use butter, as they would with other kinds of bread rolls.  Incidentally, when people use the word "butter" here, they are normally using margarine, not real butter.  Relatively few people still seem to use real butter (although when I was in the Navy, we always had real butter, because of the influence of the Washington politicians coming from those states where the dairy industry was important.)  Also, sometimes very small sandwiches are made with biscuits, generally as a breakfast food.  Finally, what the British call a biscuit we call a cookie. 

Bottom/bum- There are a host of synonyms for that particular part of the anatomy (some of them regional) although, sadly, most you don't hear very much anymore.  The choice of which to use was and remains generally dependent upon the context, including how delicate the speaker wished to be in discussing this arguably sensitive physical feature. 

Here's a list:  butt, bottom, behind, booty (only about 20 or 30 years old, at most), buns (also dates from the 1970's, and adopted because of it's resemblance to some of the previously-mentioned bread products), fanny, derierre, keister, carcass, can, posterior, rear end, rear, tusche, tuchas (from the Yiddish),  "Ass" was always regarded as vulgar and rude (essentially, it is treated as a swear-word, except on television nowadays, where they are constantly trying to be "edgy"on theory that it attracts viewers). "Butt" was also considered somewhat crass but not as bad so that it could be employed as a euphemism for "ass" in situations where swearing was prohibited but where the crass connotation was desired - for example, on television or in the movies before swearing became prevalent there, and where the producers were trying to simulate an environment where one would expect swearing to be employed, such as in military, crime, or sports contexts. 

Words like can, carcass, and keister were similarly used. We have also pretty much adopted "bum" as more polite word for the sitting down place, though you don't hear it used very often.  "Buns" is (or was, anyway) not infrequently used by women when admiring the same on a male. 

flagstaff/flagpole.  Flagstaff is more of a military or naval term.  I can't think when I have ever heard it used in a purely civilian context, apart from the name of the city in Arizona.

shoestring/laces, or shoelaces.  Interestingly, "shoestring" only seems to be used to describe something tenuous, generally some operation or task being carried out in spite of an acute shortage of the usual resources needed to do it.

As for movie and film, we use both words, but movie is much more common, "film" generally being reserved for situations where you are engaging in a serious discussion of a movie.

toilet- there are a lot of expressions for this. First, the word "toilet" can refer to either the receptacle itself or the facility generally where it is located, though the way most people use the word is to indicate the receptacle only. 

As for the receptacle itself, on an architectural plan you will see it identified by the initials W.C., for water closet, but you won't hear it anywhere else. This refers to the commode (the plumber's term), itself, not the room containing it. Similarly, only architects typically use the term "lavatory," to denote a room containing a W.C. and a sink, but no bath.  Most Americans refer to the same as "the bathroom", whether it has a bath or not.  

We also commonly, though not exclusively, say "restroom", if it is in a place other than a home or its equivalent, such as a hospital room or hotel room (unless a visitor feels uncomfortable and is trying to be too polite).  Restroom can be further changed into "men's room" and "ladies' room" and occasionally you might still hear someone say "the gents'" in reference to the fact that men's room doors used to often have a sign on them that said "Gentlemen." 

Some places will use the term "powder room;" once upon a time, when people dressed more formally for dinner, the ladies' room at a posh restaurant might go by that name.  On architectural plans for residences you may also see that term used in place of "lavatory" as discussed above, for the same reason that they may denominate the covered place where you park your car as a "porte coche" instead of a "carport."  And as previously noted, sometimes because we sometimes teach children to say "little girls room", or "little boys room," in joking, teenagers or adults might say "I've just got to hit the little boys room real fast."  If you are trying to be cute, this can be further permutated into all sorts of other expressions; when I was 18 and had just returned from my first submarine patrol with the United States Naval Reserve, I would tell my girlfriend I needed to use the "little submariners' room."  Another expression people teach young children is "potty," and I once had a very dainty blonde girlfriend who still used that expression in an effort to be delicate when she was in her mid-thirties.  Occasionally you might hear someone simply asking for the "facilities."

The term "can" is a cruder expression that was used pretty much exclusively by men, though you don't here it much anymore. In military circles, the Navy and Marines Corps still use "head" aboard ship or on base while the army uses "latrine" (I don't know what the Marines call it in the field or what Air Force calls it anyplace, but not being very impressed with that branch I would be willing to bet on "potty"). On submarines we used to call the commodes themselves by the delicately endearing term, "shitters."

trousers/pants- You almost never hear the term trousers used in the U.S. anymore, except possibly on occasion in a men's wear specialty store.  You also used to hear the word "slacks" to identify at least some long pants not part of a suit, but it seems to have gone out of fashion. Basically, for long pants we just say "pants."  As a previous writer noted, some kinds of pants are indicated simply by talking about the type, such as jeans or khakis.  When these terms are used it is assumed that long pants are intended.  For short pants we simply say "shorts," or "jeans shorts," "khaki shorts," etc.  We also have "cuttoffs," which describes shorts which have the appearance of having been made by truncating a pair of long pants without bothering to hem the legs, so that they are left with a ragged appearance.  Almost always those are made from jeans.

side walk/pavement -  Unlike others, I can't think where I've ever heard anyone call the sidewalk anything but, unless it was when I was very young and I just don't remember anymore.

In the UK these "crispy wafers" are called "crisps".

ground floor/first floor- In the States we normally use these two terms synonymously.  Occasionally you'll see an office building or similar large structure where for some reason (usually entrances at different levels) the architect denominated both a ground floor and a first floor above that, which usually causes confusion until you are made aware of it and get used to it.

taxi cab - When I was a little kid I used to call these by both names - "taxi-cab."  Nowadays pretty much everybody I know calls them just cabs, yet the word taxi is hardly extinct, and shows up other places implying door-to-door delivery, such as "take-out taxi" to describe the delivery of meals to your door.

shops and stores  - In the U.S. people normally say "store" where it seems the British more commonly use "shop."   When we use "shop" in reference to retail it is usually for particular kinds of generally small specialty store, such as gift shops, greeting card shops, optical shops, or a tailor's shop.  In this regard, the word is more typically associated with a place where work is done, rather than just merchandise being sold, so that you get various repair shops (mechanic's, auto/car repair, auto body, brakes, mufflers, shoes, televisions, computer repair, clocks & watches, etc.). 

You also still some people describe a vehicle being repaired as "in the shop" (although you could just as easily hear them say that it is "at the mechanic, " "at the dealer" (where the dealership which sells such cars also has a "service department" to repair them) or even "at the garage" (which is another name for a car repair shop, as well as a room in which to park your car) as well as of course, "at Joe's [Fred's, Dave's, Ray's, Auto Doc, etc.]"  

The word "shop" is also used sometimes to describe repair or maintenance facilities within businesses, and it used to be a slang term in the Navy for certain support facilities aboard ship. 

People will also sometimes have places in their homes to pursue their hobbies which might be referred to as workshops, woodworking shops, and the like.  The term workshop is also widely used in business or professional circles to describe a seminar of some kind.

estate agent- is called a realtor or real estate agent

We say jam just as much as we say jelly (and we also have marmalade, too)

Garden/yard - The part of one's home the British refer to as "the garden" Americans call "the yard."  When Americans use the word garden, it is in reference to a particular place (often within a yard) dedicated to growing vegetables or flowers.

***  Licensing hours have changed in the UK;  Pubs and bars can now apply to stay open 24/7.

Moreover, we don't say we are going to the pub.  More likely we would say that we are "going out," or "going out for drinks" (or "going out for a drink," though this usage is probably passe) or that we were going to a particular bar, i.e., "I'm going to the Richmond Arms (Black Lab, Boar's Head, Baker Street Pub, Gingerman, Earnie's, The Aquarium, Fuzzy's etc.).  If we are going out to a dance club rather than just a bar, we'd say we were going out to a club.

Pram -  We call this a "baby carriage" or, in it's more modern form, a "stroller".

Roundabout - this must go by more than one name in the States, depending on where you are.  Everyplace I have ever seen them (including Camp Lejuene, North Carolina and Houston, Texas) they were called traffic circles.

Car terminology:  What the British call the "hood" on a convertible car we call the "top."  We then use the word "boot" to name the little cover that goes over the top when it is down.  

I have heard that the British now use the term "truck" in addition (if not actually in preference to) "lorry".

Solicitors in the US are people who come door to door to sell things (nowadays primarily to businesses, rather than homes), or call you on the telephone, and there are tons of people with stores that say "no solicitors" on the fronts.  Lawyers in America are called either lawyers or attorneys, with the terms being 100% synonymous.  We do not have nor draw any distinction between solicitors and barristers.  This is notwithstanding the fact that for some reason there is a position in the federal government in Washington called the Solicitor General, which is a different position from the Attorney General.

gravy is a brown sauce made from meat used on turkey (and mashed potatoes and chicken-fried steak and various other things), but many Italian-Americans still refer to gravy as tomato sauce, and all the generations after them still use it.

Resume/ CV -  In my experience as a lawyer, physicians, scientists, some engineers, and similar professionals may have CV's.  Most people, including lawyers, do not.