Just a quick but extensive list of words that are different in the UK-at-large from American English, but are generally the same thing.
US: Chips (Doritos, etc)
Brit: Crisps
US: french fries, potato wedges
Brit: chips
US: Cookies (Oreos, etc)
Brit: Biscuits
US: restroom, toilet
Brit: Loo, WC, bog
US: toilet paper, TP
Brit: bog roll, loo paper
US: trunk (storage area of a car)
Brit: boot
US: going on vacation
Brit: going on holiday
US: apartments
Brit: flats
US: counterclockwise
Brit: anticlockwise
US: sneakers, tennis shoes
Brit: trainers
US: sweater, hoodie
Brit: jumper, hooded jumper
US: truck
Brit: lorry
US: bullhorn
Brit: loudhailer
US: 18-wheeler, semi
Brit: articulated lorry
US: coveralls
Brit: boiler suit
US: hood of a car
Brit: bonnet of a car
US: vest
Brit: waistcoat
US: tow truck
Brit: breakdown van
US: plastic wrap
Brit: cling film
US: crib (for a baby)
Brit: cot
US: public housing, ‘the projects’
Brit: council estate
US: alligator clip
Brit: crocodile clip
US: defroster (in a car)
Brit: demister
US: robe, bathrobe
Brit: dressing gown
US: pacifier, binky (for a baby)
Brit: dummy
US: trash, garbage
Brit: rubbish
US: ground (electrical)
Brit: earth
US: fire department
Brit: fire brigade
US: fish stick
Brit: fish fingers
US: switchblade
Brit: flick knife
US: yard, lawn (front yard, back yard, etc)
Brit: garden (front garden, back garden, etc)
US: period (punctuation.)
Brit: full stop
US: gear shift
Brit: gear lever
US: bachelor party
Brit: stag do, stag night
US: going to the hospital, in the hospital
Brit: going to hospital, in hospital
US: jelly beans
Brit: jelly babies
US: John Q Public
Brit: Joe Public
US: rummage sale, garage sale
Brit: jumble sale
US: crossing guard
Brit: lollipop (-man/lady)
US: suspenders
Brit: bracers
US: hungry
Brit: peckish
US: zucchini
Brit: courgette
US: math
Brit: maths
US: odometer (car gauge measuring distance)
Brit: milometer (‘mile-ometer’)
US: cell phone
Brit: mobile
US: newscaster, anchor
Brit: newsreader
US: tic-tac-toe
Brit: noughts and crosses
US: license plate
Brit: number plate, registration plate
US: baked potato
Brit: jacket potato
US: eggplant
Brit: aubergine
US: turtleneck
Brit: polo-neck
US: absentee ballot
Brit: postal vote
US: utility pole, telephone pole
Brit: pylon
US: jump rope
Brit: skipping rope
US: take-out, to-go order, fast food
Brit: takeaway
US: check mark the box
Brit: tick the box
US: ‘knock on wood’
Brit: ‘touch wood’
US: truck stop
Brit: transport cafe
US: subway
Brit: underground, tube
US: closet, armoire
Brit: wardrobe
US: the letter Z (‘zee’)
Brit: the letter Zed
US: fender (of a car)
Brit: wing
US: certified mail
Brit: recorded delivery
US: to get in line (to wait one’s turn for something)
Brit: to queue up
US: doing pushups
Brit: doing pressups
US: oven mitt
Brit: oven glove
US: diaper
Brit: nappy
US: popsicle/otter-pops (both brand names)
Brit: ice lollies
US: bangs (hair that hangs down in front)
Brit: fringe
US: divided highway
Brit: dual carriageway
US: fanny pack
Brit: bumbag
US: cotton candy
Brit: candy floss
US: parking lot
Brit: car park
US: soccer
Brit: football
US: gelatin, Jell-O
Brit: jelly
US: jelly (sandwich spread)
Brit: jam
US: motorcycle
Brit: motorbike, motorscooter
US: Hoveround (brand), motorized chair
Brit: mobility scooter
US: sidewalk
Brit: pavement, footpath
US: gasoline (fuel for vehicles)
Brit: petrol
US: in the mail
Brit: in the post
US: eraser (such as for pencils)
Brit: rubber
US: schedule
Brit: timetable
US: multiplication tables
Brit: times-tables
US: flashlight
Brit: torch
US: windshield
Brit: windscreen
US: advice columnist
Brit: agony aunt
US: German Shepherd (dog)
Brit: Alsatian
US: parka-style jacket
Brit: anorak
US: lawyer, attorney
Brit: barrister, solicitor
US: ink pen, ball-point pen
Brit: biro
US: parenthesis
Brit: round brackets
US: downtown
Brit: city centre
US: stove
Brit: cooker
US: resume (job application document)
Brit: CV
US: tuxedo, sport coat, suit coat
Brit: dinner jacket
US: drunk driving
Brit: drink driving
US: school principal
Brit: headmaster
US: vacuum cleaner
Brit: hoover
US: quotation marks
Brit: inverted commas
US: ladybug
Brit: ladybird
US: go check at lost and found
Brit: go check at lost property
US: underwear, undies
Brit: pants
US: baby carriage, stroller
Brit: pram, push chair
US: backpack
Brit: rucksack
US: wrench
Brit: spanner
US: streetcar, trolley
Brit: tram
US: crosswalk
Brit: zebra crossing
US: wouldn’t touch with a ten-foot pole
Brit: wouldn’t touch with a bargepole
US: dame, broad, gal
Brit: bird
US: bus
Brit: coach
US: male friends, buddies, bros, the guys,
Brit: chaps, mates, lads
US: skeletons in the closet
Brit: skeletons in the cupboard
US: fart
Brit: trump
US: umbrella
Brit: brolly
US: calling someone collect
Brit: making a reverse-charge call
US: ground beef
Brit: mince
US: dead tired, exhausted, beat
Brit: knackered
US: student discount, elderly discount
Brit: student concession, elderly consession
US: on a fixed income
Brit: pensioner
US: pharmacist / pharmacy
Brit: chemist / chemist shop
US: down in the dumps, depressed
Brit: gutted
US: epic fail, jack up, mess up royally
Brit: cock up
US: barf, hurl, throw up, vomit, toss one’s cookies, retch
Brit: chunder
US: shady, creepy
Brit: dodgy
US: delish, yummy
Brit: scrummy
US: one’s own body
Brit: one’s rig
US: awesome
Brit: brilliant
..and more to be added as I come across them =)
Credits: my own experience listening to BBC Radio, Oxford Dictionaries, Bored Panda, GrammarCheck, Englisch-hilfen, Wikipedia, JustEnglish.me, How Stuff Works, Anglotopia,