signature vs signature tune

signature and signature tune both are nouns.

Word	Noun	Adjective	Verb	Adverb
signature	Yes	No	No	No
signature tune	Yes	No	No	No

As nouns, signature and signature tune are synonyms defined as:

signature and signature tune: a melody used to identify a performer or a dance band or radio/tv program

Other synonyms of signature include theme song.

signature (noun)	signature tune (noun)
a distinguishing style	a melody used to identify a performer or a dance band or radio/tv program
your name written in your own handwriting
a sheet with several pages printed on it; it folds to page size and is bound with other signatures to form a book
the sharps or flats that follow the clef and indicate the key
a melody used to identify a performer or a dance band or radio/tv program