melodic theme vs melodic phrase

melodic theme and melodic phrase both are nouns.

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

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

Other hypernyms of melodic theme include air, line, melodic line, melody, strain, tune.

melodic theme (noun)	melodic phrase (noun)
(music) melodic subject of a musical composition	a succession of notes forming a distinctive sequence