Both of my grandfathers died LONG before I was born.
My paternal grandmother was Grandmama Lulu and my maternal grandma is Nana
My great grandmother on my mother's side was called Big Mama
__________________
"OP, you have 99 problems, but a sorority ain't one"-Alumiyum
Grandmother/Grandaddy; Grandmother/Grandfather. We were very formal like that.
When my parents became grandparents, they weren't down with being called "Grandma/Grandpa," so they have pet names based on their real names. My niece and nephew call my dad "Daddy [his first name]," and I doubt any man I marry will be down with that. So it's likely that my kids will probably go to the Grandma/Grandpa route.
Maternal Grandparents
Grandmother== called her Nonnie
Grandfather (did not meet him until I was 16 and only met 2X in my life) referred to him as my mother's father
Paternal Grandparents
Grandmother (very senile by the time I was born) Bubbie
Grandfather (died before I was born) my father referred to him as my Zeyde.
My kids use the following grandparent terms
Maternal grandparents
Gramma
Papa
Paternal grandparents
Grandmother-- her name (she died before they were born)
Grandfather-- Honey
Honey's Wife-- Honey Bear
Step mother's mother--Gramma (name)
Stepmother's stepfather Grandpa (name)
Step mother's step mother has name first name as stepmother-- Different (name)
Stepmother's father-- Babbo