tiddler vs youngster

tiddler and youngster both are nouns.

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

As nouns, tiddler and youngster are synonyms defined as:

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

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