sweater

As nouns the difference between sweater and crewneck

is that sweater is a knitted jacket or jersey, usually of thick wool, worn by athletes before or after exercise while crewneck is a round neckline with a ribbed texture.

As nouns the difference between sweater and guernsey

is that sweater is a knitted jacket or jersey, usually of thick wool, worn by athletes before or after exercise while guernsey is a seaman's knitted woolen sweater, similar to a jersey.