unambitious vs ambitionless

unambitious and ambitionless both are adjectives.

Word	Noun	Adjective	Verb	Adverb
unambitious	No	Yes	No	No
ambitionless	No	Yes	No	No

As adjectives, unambitious and ambitionless are synonyms defined as:

unambitious and ambitionless: having little desire for success or achievement

unambitious (adjective)	ambitionless (adjective)
having little desire for success or achievement	having little desire for success or achievement