toddler vs small fry

toddler and small fry both are nouns.

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

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

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

toddler (noun)	small fry (noun)
a young child who is just beginning to walk	someone who is small and insignificant
	a young person of either sex