motif vs melodic theme

motif and melodic theme both are nouns.

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

As nouns, melodic theme is a hypernym of motif; that is, melodic theme is a word with a broader meaning than motif:

Other hypernyms of motif include idea, musical theme, theme.

motif (noun)	melodic theme (noun)
a design or figure that consists of recurring shapes or colors, as in architecture or decoration	(music) melodic subject of a musical composition
a unifying idea that is a recurrent element in literary or artistic work
a theme that is repeated or elaborated in a piece of music