First, let's get some of the language differences straightened out. Even though both English and Americans speak English, there are some mighty big differences between what's being said by who. So, I've been putting this together over the past several months:

American - British Lexicon: A work in progress.
Entries in no particular order. A word of caution, words with an * should not be used in polite conversation! :-)

• American - British

• Cookies - Biscuits

• Biscuits - Rolls
• French Fries - Chips
• Potato Chips - Potato Crisps
• Oat Meal - Porridge
• Sidewalk - Pavement
• Bathroom - Loo
• Sales Tax - VAT (Value Added Tax)
• Cell Phone - Mobile (pronounced Mo-Bile)
• Garbage Can - Dust Bin
• Trash Can (small) - Bin
• Mall - Shops
• Pitcher - Jug
• Leash - Lead
• Stove - Hob
• Mail - Post
• Really Pleased - Chuffed
• Whine - Whinge
• Aroused (Horny) - Randy
• Flashlight - Torch
• Closet - Cupboard
• Booger - Bogey
• Kiss/Make Out - Snog
• Dang/D*mn - Bugger*
• Jerk/Idiot - Git
• Eraser - Rubber . . . this one'll get you in trouble if you ain't careful.
• Truck - Lorry
• Car Hood - Bonnet
• Car Trunk - Boot
• Passionate Sex - Rodgering*
• Bangs - Fringe
• Braids - Plaits
• Commercial - Advert
• Popsicle - Lolly
• Soccer - Football
• American - Yank
• Men's underwear - Pants or Y Fronts
• Men's Pants - Trousers
• Drug Store - Chemist's
• Doctors Office - Surgery
• Surgeon/Dr. - Mr/Mrs Surname (This is in the case of senior specialists or residents)
• Last Name - Surname
• Supper/Dinner - Tea (not to be confused with Tea Time, a formal afternoon ritual)
• Macys - Marks & Spencer
• Wrench - Spanner
• Diaper - Nappy
• Subway - Tube
• High School - Secondary School or College
• School Principle - Headmaster or Head Teacher
• Expensive or High - Posh Society
• College - University
• Raise (as in Pay) - Rise
• Friend or Buddy - Mate
• See Ya - Cheers
• Guy - Bloke
• Vacuum (verb) - Hoover
• Cheesecloth - Muslin
• Cotton Candy - Candy Floss
• Downspout - Drain Pipe
• Duplex - Semi-detached House
• Ground Beef - Beef Mince
• Ground Round - Best Mince
• Hush Puppies - Corn Meal Fritters
• Lightning Bug - Glow Worm
• Overpass - Flyover
• Realtor - Estate Agent
• Thanks - Cheers
• Station Wagon - Estate Car
• Sedan - Saloon
• Pacifier - Baby's Dummy
• Yard - Garden
• VCR - Video Recorder
• Corn - Maize
• Zucchini - Courgette
• Elevator - Lift
• First Floor - Ground Floor
• Second Floor - First Floor
• US Postal Service - Royal Mail
• Acetaminophen - Paracetamol
• Ibuprofen - Brufen
• Panty Hose - Tights
• Thigh Highs - Holdups
• Leotards - Leggings
• Hill or Mount - Fell
• Vest - Waist Coat
• Tank Top - Vest
• Sweater - Cardigan
• Jersey - Jumper
• Hooded Jersey - Hoodie
• Aluminum - Aluminium (pronounced AL lumMIN EEum)
• Stove Top - Hob
• Fanny Pack - Bum Bag
• Woman's Privates - Fanny*
• Fanny - Bum