allograph vs signature

allograph and signature both are nouns.

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

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

allograph (noun)	signature (noun)
a variant form of a grapheme, as `m' or `M' or a handwritten version of that grapheme	a distinguishing style
a signature written by one person for another	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