bairn vs nestling

bairn and nestling both are nouns.

Word	Noun	Adjective	Verb	Adverb
bairn	Yes	No	No	No
nestling	Yes	No	No	No

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

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

bairn (noun)	nestling (noun)
a child: son or daughter	young bird not yet fledged
	a young person of either sex