melodic theme vs motive

melodic theme and motive both are nouns.

Word	Noun	Adjective	Verb	Adverb
melodic theme	Yes	No	No	No
motive	Yes	Yes	No	No

As nouns, motive is a hyponym of melodic theme; that is, motive is a word with a more specific, narrower meaning than melodic theme:

Other hyponyms of melodic theme include motif, statement, variation.

melodic theme (noun)	motive (noun)
(music) melodic subject of a musical composition	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

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