smash hit vs smasher

smash hit and smasher both are nouns.

Word	Noun	Adjective	Verb	Adverb
smash hit	Yes	No	No	No
smasher	Yes	No	No	No

As nouns, smasher is a hypernym of smash hit; that is, smasher is a word with a broader meaning than smash hit:

smash hit: an unusually successful hit with widespread popularity and huge sales (especially a movie or play or recording or novel)
smasher: a conspicuous success

Other hypernyms of smash hit include bang, hit, smash, strike.

smash hit (noun)	smasher (noun)
an unusually successful hit with widespread popularity and huge sales (especially a movie or play or recording or novel)	a conspicuous success
	a very attractive or seductive looking woman
	a person who smashes something