Maternal - Granny
Paternal - Nana. Though this was highly objected to by my mother when I was first born (she wrote thankyou notes etc to 'Granny and Grandad', but they always wrote 'Nana and Grandy' and insisted that that was what they were going to be called) so it stuck. Though I quite like the fact that I don't know anybody else who calls their grandad 'Grandy'.
Well I only ever knew one of my grandmothers because the other died even before my dad met my mum. I used to call the one I knew 'Nonna' (meaning 'Granny' in Italian) because she thought it sounded less old than 'Granny'
We don't have any Italian roots, it's just that she preferred being called that