youth vs younker

youth and younker both are nouns.

Word	Noun	Adjective	Verb	Adverb
youth	Yes	No	No	No
younker	Yes	No	No	No

As nouns, youth and younker are synonyms defined as:

Other synonyms of youth include spring chicken, young person.

youth (noun)	younker (noun)
the freshness and vitality characteristic of a young person	a young person (especially a young man or boy)
young people collectively
a young person (especially a young man or boy)
early maturity; the state of being young or immature or inexperienced
the time of life between childhood and maturity
an early period of development