motive vs motivative

motive is a noun but motivative is not a noun.

Word	Noun	Adjective	Verb	Adverb
motive	Yes	Yes	No	No
motivative	No	Yes	No	No

As adjectives, motive and motivative are synonyms defined as:

Other synonyms of motive include motivating.

motive (noun)	motivative (noun)
the psychological feature that arouses an organism to action toward a desired goal; the reason for the action; that which gives purpose and direction to behavior
a design or figure that consists of recurring shapes or colors, as in architecture or decoration
a theme that is repeated or elaborated in a piece of music

motive (adjective)	motivative (adjective)
causing or able to cause motion	impelling to action
impelling to action