AR I feel falls down on this point for not indicating the terribly inadequate supply system of the Americans. From the '75 invasion of Canada, where the only commodity not in short supply was inexperience, right through to Nathan Green's brilliant campaign of 1780, the Americans had to operate through a logistical nightmare. 1776, on the other hand, tends to make supply units a little too plentiful, especially in winter. This does lead to the British being able to fight on when cut off from the coast. As in reality however, a conscientious British commander will avoid this situation most of the time.
Winter is the next point of discussion.
In the Eighteenth century few operations were undertaken in winter. A lack of adequate billeting facilities coupled with a very incomplete medical knowledge could lead to severe hardships and losses amongst the troops. Both games handle winter differently. This fraction decreases by the year. Also the British may neither move nor fight and the Americans have their movement allowance dropped, from five to two.