imperfective vs durative

imperfective and durative both are nouns.

Word	Noun	Adjective	Verb	Adverb
imperfective	Yes	No	No	No
durative	Yes	No	No	No

As nouns, durative is a hypernym of imperfective; that is, durative is a word with a broader meaning than imperfective:

imperfective: aspect without regard to the beginning or completion of the action of the verb
durative: the aspect of a verb that expresses its duration

Other hypernyms of imperfective include durative aspect.

imperfective (noun)	durative (noun)
aspect without regard to the beginning or completion of the action of the verb	the aspect of a verb that expresses its duration