what's the difference between Nasılsınız and Nasılsın

Both of them mean how are you in English, but what's the difference in turkish.

In which situation should Nasılsınız be used? and in which situation should Nasılsın be used?

Tesekür ederim!

They both mean How are you 

but nasılsın is for sen and nasılsınız is for siz

you should use nasılsınız if u are asking it to more than one person or in the sitiuations that requires respect like the person you are talking is older than you or you just met the  person