nipper vs youngster

nipper and youngster both are nouns.

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

As nouns, nipper and youngster are synonyms defined as:

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

nipper (noun)	youngster (noun)
a grasping structure on the limb of a crustacean or other arthropods	a young person of either sex
a young person of either sex