bellbottom trousers vs bellbottom pants

bellbottom trousers and bellbottom pants both are nouns.

Word	Noun	Adjective	Verb	Adverb
bellbottom trousers	Yes	No	No	No
bellbottom pants	Yes	No	No	No

As nouns, bellbottom trousers and bellbottom pants are synonyms defined as:

bellbottom trousers and bellbottom pants: (used in the plural) trousers with legs that flare; worn by sailors; absurdly wide hems were fashionable in the 1960s

Other synonyms of bellbottom trousers include bell-bottoms.

bellbottom trousers (noun)	bellbottom pants (noun)
(used in the plural) trousers with legs that flare; worn by sailors; absurdly wide hems were fashionable in the 1960s	(used in the plural) trousers with legs that flare; worn by sailors; absurdly wide hems were fashionable in the 1960s