Okay Jen -
An American biscuit is a soft fluffy scone. http://en.wikipedia.org/wiki/Biscuit_(bread)
An American cookie is an English biscuit.
An American cracker is also an English biscuit but used to eat with cheese or soups. http://en.wikipedia.org/wiki/Cracker_(food)
An American English muffin, is a round, yeast-leavened form of bread almost always dusted with cornmeal http://en.wikipedia.org/wiki/Muffin_(English)
The closest thing we have to Crumpets is the English muffin
An American bread roll http://en.wikipedia.org/wiki/Bread_roll
It changed in the American colonies as early as the 1500's.
Too many Irish convicts from the Poor Houses and Scottish POWs.... they really had no earthy clue which was which, only hearing the names from their English masters ....cookies, crackers, crumpets, corn, maize ......words are the first things that assimulates to a new situations.
Here's you a bonus;
American Jello ---- Gelatin dessert, referred to as jelly in Britain, callrf by its brand name Jell-O
British Jelly ---- Gelatin dessert, referred to as jelly in Britain and other countries, popular brands include Jell-O
American Jelly ---- Fruit preserves, called 'jelly' in North America, specifically a clear fruit spread