Great or Grand?

[rogo]

What is the difference between a great or a grand niece/nephew in a family relationship? I have heard the term great niece/nephew, but some say it's the grand niece/nephew.

[Quizmonster]

There is no difference.

[shaneystar2]

I have a myriad of them and call them my great nieces and nephews .I call their offspring the great great (s ) but more often than not .... the grand (s )!
Only because "grand" is less of a mouthful than "great great" !
But they are .... as QM says the same .
Grand grands doesn't have the same ring to it though !!