Instead of;
Right away they say Straight away
Sweaters they say Jumpers
Vacation they say Holiday
Friends they say Mates
French Fries they say Chips
Butt they say Bum
Right away, I’ll point out that I’ll happily wear sweaters, my friend. 
(Correct on the others, though 
)
Nope - Arse. Always arse. Even the Queen.
The obvious ones:
flashlight > torch
sidewalk > pavement
cookies > biscuits
yard > garden
(car)hood > bonnet
(car)trunk > boot
eggplant > aubergine
pissed > angry
drunk > pissed
zucchini > courgette
jello > jelly
pharmacist > chemist
fall > autumn
candy > sweets
chips > crisps
gas > petrol
Football means football.
American football means that rugby abomination and we call Baseball “rounders” and Basketball “netball”.
We seem to have different meanings for the word “beer” too. For you it’s a fizzy soft drink - for us it’s something that gets you pissed (see above). There a similar confusion about the word “cider”. This is always alcoholic in Britain (and drunk by 17 year old chave in bus shelters).
Here’s a sentence with quite different meanings on either side of the pond:
“Girls these days wear their pants so low that you can see their fannies”.
(Some of this has probably been said before, but what the heck)
In the UK we have the Royal Mail and our letters are delivered by Postmen (which also includes Postwomen), whereas the US Postal Service uses Mailmen/women.
We park on our driveways, you drive on your parkways.
Then there are the spellings: e.g. we never spell Defence with an S; we use C and S to differentiate between noun and verb in words like Licence/License and Practice/Practise; we double final consonants in words like traveller and pannelled; we spell colour, neighbour etc with a U.
We pronounce the H in Herb.
When we play football, the principal means of propelling the ball is by foot.
And when we play rugby, we don’t cover our entire bodies in foam.
Y’know, you really have to come to the US sometime and have some of our beer. It ain’t all Budweiser anymore. Even in my blue-collar, low-educated family, most people enjoy a good strong beer when offered one.
[Standing in between Heather Mitts and Linda Cohn (yay me!)]
Ooh, ooh, say “get your knickers in a twist!”
[/sibHMaLC(ym!)]
clerk = clerk, but in England it’s pronounced “clark”
And then there’s “aluminum” which in England is not only pronounced differently, but also spelled differently - “aluminium.”
I have a friend who was born and raised in England, but who has been in the US since the mid-60s. Some of the language differences really baffled her (like when she asked for a bowl of jelly and got jam, instead of gelatin.) And for the record, she says “bum” and not “arse.”
“Britain and America are two countries separated by a common language” - Robert Benchley.
“Britain and America are two countries separated by a common language and a lot of fish.” - Eddie Izzard
Unfortunately some folks think that this means to be angry or perturbed about someone or something when it actually means to get an erection, IMHO.
On the OP: Brits: The victim was sent to hospital. The student went to university.
U.S.'n: We put “the” in front of “hospital” and “university”.
I think the “separated…” quotation was from either Oscar Wilde or Beroge Berbard Shaw, but msut say I like the Eddie Izzzard one. 
US - write your congressman (or whatever, you get the point)
British - write to your (whatever)
US - “I was tossing all night” = I didn’t sleep well
British - “I was tossing and turning all night” = I didn’t sleep well
British - “I was tossing all night” = I didn’t sleep well because I was masturbating like a motherfuck.
GAR-aaahj (US) = gahr-IDJ (UK)
The boundary between the pavement ( side-walk ) and the road . UK= kerb , US=curb . (We do use curb when talking about restricting or restraining something )
When looking for a place to stay . UK = accommodation , US = accommodations.
and of course maths and math.
Some more:
UK->US
fag->cigaratte
faggot->a type of meatball
rubber->eraser
bollocks->testicles (used as an expletive)
My brother works in a coffee shop, and he was telling me about a British co-worker of his who asks customers “Do you want this for here or to take away?”
Well if we’re going to talk about obvious Mangetout,
snow peas > mangetout
and
rutabaga >swede
zucchini>corgette
arugula>rocket
You’re right. Sorta It’s George Bernard Shaw. It’s been erroneously attributed to Oscar Wilde, and I KNEW it wasn’t Wilde, but I blanked on who it actually was and came up with Benchley.