juvenescence vs ontogenesis

juvenescence and ontogenesis both are nouns.

Word	Noun	Adjective	Verb	Adverb
juvenescence	Yes	No	No	No
ontogenesis	Yes	No	No	No

As nouns, ontogenesis is a hypernym of juvenescence; that is, ontogenesis is a word with a broader meaning than juvenescence:

juvenescence: the process of growing into a youth
ontogenesis: (biology) the process of an individual organism growing organically; a purely biological unfolding of events involved in an organism changing gradually from a simple to a more complex level

Other hypernyms of juvenescence include development, growing, growth, maturation, ontogeny.

juvenescence (noun)	ontogenesis (noun)
the process of growing into a youth	(biology) the process of an individual organism growing organically; a purely biological unfolding of events involved in an organism changing gradually from a simple to a more complex level