How do you say grandmother in Chinese?

In Chinese language they have separate the mother's side's grandmother and father's side's grandmother.

For father's side: 奶奶 [nǎi nai] or 祖母 [zǔ mǔ]

For mother's side: 外婆 [wài pó] or 外祖母 [wài zǔ mǔ]