monkey vs youngster

monkey and youngster both are nouns.

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

As nouns, youngster is a hypernym of monkey; that is, youngster is a word with a broader meaning than monkey:

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

monkey (noun)	youngster (noun)
any of various long-tailed primates (excluding the prosimians)	a young person of either sex
one who is playfully mischievous

monkey (verb)	youngster (verb)
do random, unplanned work or activities or spend time idly
play around with or alter or falsify, usually secretively or dishonestly