bairn vs small fry

bairn and small fry both are nouns.

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

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

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

bairn (noun)	small fry (noun)
a child: son or daughter	someone who is small and insignificant
	a young person of either sex