knee pants vs breeches

knee pants and breeches both are nouns.

Word	Noun	Adjective	Verb	Adverb
knee pants	Yes	No	No	No
breeches	Yes	No	No	No

As nouns, knee pants and breeches are synonyms defined as:

knee pants and breeches: (used in the plural) trousers ending above the knee

Other synonyms of knee pants include knee breeches, knickerbockers, knickers.

knee pants (noun)	breeches (noun)
(used in the plural) trousers ending above the knee	(used in the plural) trousers ending above the knee