granny vs gran

granny and gran both are nouns.

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

As nouns, granny and gran are synonyms defined as:

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

granny (noun)	gran (noun)
a reef knot crossed the wrong way and therefore insecure	the mother of your father or mother
the mother of your father or mother
an old woman