Nanna is a synonym of nan.
As nouns the difference between nanna and nan
is that nanna is grandmother while nan is (british) affectionate name for a grandmother or nan can be (naan).
nan
English
Etymology 1
Possibly derived from a (etyl) language.
Noun
(
en noun)
(British) Affectionate name for a grandmother.
Synonyms
* nana
* nanna
Etymology 2
From (etyl) .