sweep away vs impress

sweep away is not a noun while impress is a noun.

Word	Noun	Adjective	Verb	Adverb
sweep away	No	No	Yes	No
impress	Yes	No	Yes	No

As verbs, impress is a hypernym of sweep away; that is, impress is a word with a broader meaning than sweep away:

Other hypernyms of sweep away include affect, move, strike.

sweep away (noun)	impress (noun)
	the act of coercing someone into government service

sweep away (verb)	impress (verb)
eliminate completely and without a trace	dye (fabric) before it is spun
overwhelm emotionally	produce or try to produce a vivid impression of
	mark or stamp with or as if with pressure
	take (someone) against his will for compulsory service, especially on board a ship
	reproduce by printing
	impress positively
	have an emotional or cognitive impact upon