youngster vs tiddler

youngster and tiddler both are nouns.

Word	Noun	Adjective	Verb	Adverb
youngster	Yes	No	No	No
tiddler	Yes	No	No	No

As nouns, youngster and tiddler are synonyms defined as:

Other synonyms of youngster include child, fry, kid, minor, nestling, nipper, shaver, small fry, tike, tyke.

youngster (noun)	tiddler (noun)
a young person of either sex	a young person of either sex