Brynda and I share the same grandparents. My grandchildren call me Babsie. My children’s paternal grandparents were Memaw and Grandaddy.
Some others I have heard lately are Gigi, Ninna, Tally, Lala and Boomie for grandmothers. For grandfathers, Big Pop, Da, Pop-pop, and Big Daddy are some I have run across. My best friend picked Omi for her name after hearing our mother called that.
Mum (It’s so easy to type when you have six fingers on each hand)
What kind of gift do you give a guy with 12 fingers?
Firecrackers!
I was born in the South. I never heard of Nana until I became an adult. I thought that it was some form of Aunt.
Maternal Grandparents: Granny & Grandpa
Paternal Grandparents: Grandma & Grandaddy
On Mom’s side, Grandma Mast when I was a child. When my daughter was small, learning to talk, she adopted Grandpa’'s nickname for Grandma, “Peen”, short for Pauline, and that name stuck. Grandma Peen til she passed in 08. Dad’s side - my brother and I called her Grandma Lucas. Then my daughter, the creative voice, decided to use her first name, Wilma, and Grandma Wilma she remained til her death in 2010 at age 92. Is there a Grandpa thread? 
OK. my parents were both born in Puerto Rico so I haven’t seen these yet.
Maternal: Mama & Papa (accent on the second syllable)
Paternal: Mama Mia & Papa Pin (because little kids apparently can’t say Maria & Crispin)
My step-dad’s parents are Ohioans who’s folks only spoke German, so I don’t know if this is common, but their preferred titles were Bubba & Pop Pop. I just called them Lue & Ross.
I called my grandmothers Grandma [last name] or just Grandma.
My kids call their grandmothers Grandma [first name]. There is a very kind older woman in our church who has “adopted” my children as her psuedo-grandchildren; my kids call her Oma at her request.
Mère on my Cajun mother’s side and Grandmother on my father’s side.
Never met any of my grandparents - one grandmother and one grandfather died 25-30 years before I was born; the remaining two lived several states away and died when I was five or six. I remember hearing my sister once refer to our maternal grandmother as “Grandmommy.”
My wife called her grandmothers “Grandma” and “Nana” - I can’t remember which was which.
My mother died 11 years before the elder of my girls was born. They call my mother-in-law “Grandma.”
My ex’s grandmother and mother lived together; her kids called them both “Grandma [LastName].”
Paternal Great-Grandmother was “Nana.”
Paternal Grandmother was “Missy.”
Maternal Grandmother - passed before we were born.
Maternal Step-Grandmother was “MaMaw.”
New Hampshire - Paternal Great-Grandmother was “Nana.”
New Hampshire - Paternal Grandmother was “Missy.”
Georgia - Maternal Grandmother - passed before we were born.
Georgia - Maternal Step-Grandmother was “MaMaw.”
My maternal grandparents are Bomie and Poppi (Eastern European Jewish). My paternal are/were grandmother (or grandma) and grandfather (Irish).
My paternal grandmother was Ukrainian and we called her Baba. My grandfather was Gido, though he died when I was quite young.
On my mother’s side, we didn’t really have a name for her mother. She was not a particularly warm person and apparently she was worried we might come up with something silly to call her, like Gaga, and we were never told what she did want to be called. When we got older, my brother and I referred to her by her first name, though never to her face. My maternal grandfather died before I was born.
Lola.
On my fathers side, they were Grandma and Grandpa. my great grandmother (grandpa’s mom) we called baba, short for babička (Slovak for grandma). On my mother’s side, it was Grandma Carol and Grandpa Larry.
Back when I still had both my grandmothers I called one “Grandma surname” and the other “Grandma” I only saw the former two or three times a year, while the latter, my maternal grandmother, I saw often, as she lived in the same coty as we did. She was also less reserved, mor laid back than my paternal grandmother.
I called my Father’s parents “Granny Janny(her name was Jan) and Grandad”. They’re West-Coast.
I called my Mother’s parents, “Grammie and Papa.” They’re West-Coast.
I call my Stepfather’s parents, “Gma (Gee-maw) and Gpa (Gee-paw)”. They’re East-Coast.
And I call my Stepmother’s mom “Amm(Her name was Alma)”. She is southern.
I call my maternal grandmother Aaji. It’s the Marathi word for grandmother. I haven’t seen my paternal grandmother in over 20 years (just because I haven’t been to India and she hasn’t been here), but I would call her the same thing if I did.
My grandmother, who was very much upper class, was always granny.
My paternal grandparents and maternal great-grandparents came from Poland, so we called our grandmothers (including my mom, now that she’s a grandmother) Busi, pronounced like bushy. Grandfathers were addressed as Dziadzi, pronounces JA-jee. In fact, all of my friends referred to my grandparents by these Polish titles, just as my daughter’s and niece’s/nephew’s friends call my mom Busi.