signature tune vs signature

signature tune and signature both are nouns.

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

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

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

Other synonyms of signature tune include theme song.

signature tune (noun)	signature (noun)
a melody used to identify a performer or a dance band or radio/tv program	a distinguishing style
	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