Qual è la differenza? That letter C with the thing doesn't exist in italian, the Z is used instead.
I believe that you wanted to ask OPPURE o O. They are synonims with the very slight difference in meaning or in use. The O is mostly in use although you can say oppure/ovvero...
Vieni tu o/oppure tuo fratello.
Fai quel che ti dico o/oppure vattene!