theme vs melodic phrase

theme and melodic phrase both are nouns.

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

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

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

theme (noun)	melodic phrase (noun)
a unifying idea that is a recurrent element in literary or artistic work	a succession of notes forming a distinctive sequence
the subject matter of a conversation or discussion
an essay (especially one written as an assignment)
(music) melodic subject of a musical composition
(linguistics) the form of a word after all affixes are removed

theme (verb)	melodic phrase (verb)
provide with a particular theme or motive