unripened vs immature

unripened and immature both are adjectives.

Word	Noun	Adjective	Verb	Adverb
unripened	No	Yes	No	No
immature	No	Yes	No	No

As adjectives, unripened and immature are synonyms defined as:

Other synonyms of unripened include green, unripe.

unripened (adjective)	immature (adjective)
not fully developed or mature; not ripe	not yet mature
	characteristic of a lack of maturity
	(used of living things especially persons) in an early period of life or development or growth
	(of birds) not yet having developed feathers
	not fully developed or mature; not ripe