granny vs grandmother

granny and grandmother both are nouns.

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

As nouns, granny and grandmother are synonyms defined as:

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

granny (noun)	grandmother (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