autograph vs signature

autograph and signature both are nouns.

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

As nouns, signature is a hypernym of autograph; that is, signature is a word with a broader meaning than autograph:

autograph (noun)	signature (noun)
something written by one's own hand	a distinguishing style
a person's own signature	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

autograph (verb)	signature (verb)
mark with one's signature