imp vs small fry

imp and small fry both are nouns.

Word	Noun	Adjective	Verb	Adverb
imp	Yes	No	No	No
small fry	Yes	No	No	No

As nouns, small fry is a hypernym of imp; that is, small fry is a word with a broader meaning than imp:

Other hypernyms of imp include child, fry, kid, minor, nestling, nipper, shaver, tiddler, tike, tyke, youngster.

imp (noun)	small fry (noun)
one who is playfully mischievous	someone who is small and insignificant
(folklore) fairies that are somewhat mischievous	a young person of either sex