gran vs grandmother

gran and grandmother both are nouns.

Word	Noun	Adjective	Verb	Adverb
gran	Yes	No	No	No
grandmother	Yes	No	No	No

As nouns, gran and grandmother are synonyms defined as:

Other synonyms of gran include grandma, grannie, granny, nan, nanna.

gran (noun)	grandmother (noun)
the mother of your father or mother	the mother of your father or mother