knock against vs butt against

knock against and butt against both are verbs.

Word	Noun	Adjective	Verb	Adverb
knock against	No	No	Yes	No
butt against	No	No	Yes	No

As verbs, knock against and butt against are synonyms defined as:

Other synonyms of knock against include bump into, jar against, run into.

knock against (verb)	butt against (verb)
collide violently with an obstacle	lie adjacent to another or share a boundary
	collide violently with an obstacle