Chinese languages

I have a question for a story I'm writing, and I would be very grateful if people could help me with this!

What would someone call his Chinese grandfather? Would he use different words depending on whether he is close to his grandfather or not? Would he use different words depending on whether he is speaking directly to his grandfather or speaking about his grandfather to someone else? Are the words different in different Chinese dialects?

I would also like to know the answers to the same questions about "grandmother".

Thanks! (^_^)

grandfather:
Mother's father:外祖父,外公,老爷
father's father:祖父,爷爷

grandmother:
mother's mother:外祖母,外婆,姥姥
father's mother:祖母,奶奶

Q:Would he use different words depending on whether he is close to his grandfather or not?
A:it seems like that there's no difference.

Q:Would he use different words depending on whether he is speaking directly to his grandfather or speaking about his grandfather to someone else?
A:there's no difference.
in fact,there's ddifference between "mother's father" and father's mother in Chinese

Q:Are the words different in different Chinese dialects?
A:sorry ,i speak mandarin...so i can not tell you the exact answer.

Thank you very much! Your response was very helpful.