britches vs knickers

britches and knickers both are nouns.

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

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

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

britches (noun)	knickers (noun)
(used in the plural) informal term for breeches	(used in the plural) underpants worn by women
	(used in the plural) trousers ending above the knee