My maternal grandmother is called nana. We just called her grandma growing up. But when the great grandkids came along, she had no intention of letting herself be called great grandma. So nana was she named.
My maternal grandfather passed away 12 years ago and we called him pops.
My paternal grandparents are called "my father's parents". We aren't close so there is no need to address them in any way.
This is no lie my two children call my husbands parents Weenie and Stinky... and now so does everyone else. My mom is Mom Mom and when my dad was alive he was Pop Pop