youngster vs kid

youngster and kid both are nouns.

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

As nouns, youngster and kid are synonyms defined as:

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

youngster (noun)	kid (noun)
a young person of either sex	young goat
	a young person of either sex
	a human offspring (son or daughter) of any age
	soft smooth leather from the hide of a young goat

youngster (verb)	kid (verb)
	be silly or tease one another
	tell false information to for fun