grandpa vs gramps

grandpa and gramps both are nouns.

Word	Noun	Adjective	Verb	Adverb
grandpa	Yes	No	No	No
gramps	Yes	No	No	No

As nouns, grandpa and gramps are synonyms defined as:

Other synonyms of grandpa include grandad, granddad, granddaddy, grandfather.

grandpa (noun)	gramps (noun)
the father of your father or mother	the father of your father or mother