My brother (who has a different father then me) calls his greek grandmother ya-ya (that's probably not how to spell it).
And our American grandmother is grandma, gran'ma, gram, grams,or granny. Sometimes it's Moose but I forget why, some sort of inside joke I never learned. And on really rare occasions it's granny putt-bomber.. (said more like but) something about my mom drawing her a picture of a bomb (as a kid) that said "putt putt".
My grandma on my dad's side was dead Way before me, so I never got to call her anything.
Well we have a different way of going about it at our house. My parents divorced and my dad is remarried and my mom is not. Then my kids have my hubbies parents. So for us it's Grandma Jane, Grandma Bonnie, Grandma Marielin. Just to keep everyone straight!