quick study vs learner

quick study and learner both are nouns.

Word	Noun	Adjective	Verb	Adverb
quick study	Yes	No	No	No
learner	Yes	No	No	No

As nouns, learner is a hypernym of quick study; that is, learner is a word with a broader meaning than quick study:

quick study: someone able to acquire new knowledge and skills rapidly and easily
learner: someone (especially a child) who learns (as from a teacher) or takes up knowledge or beliefs

Other hypernyms of quick study include assimilator, scholar, student.

quick study (noun)	learner (noun)
someone able to acquire new knowledge and skills rapidly and easily	someone (especially a child) who learns (as from a teacher) or takes up knowledge or beliefs
	works for an expert to learn a trade