britches vs knickerbockers

britches and knickerbockers both are nouns.

Word	Noun	Adjective	Verb	Adverb
britches	Yes	No	No	No
knickerbockers	Yes	No	No	No

As nouns, knickerbockers is a hypernym of britches; that is, knickerbockers is a word with a broader meaning than britches:

Other hypernyms of britches include breeches, knee breeches, knee pants, knickers.

britches (noun)	knickerbockers (noun)
(used in the plural) informal term for breeches	(used in the plural) trousers ending above the knee