quick study vs assimilator

quick study and assimilator both are nouns.

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

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

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

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

quick study (noun)	assimilator (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