Both Mario and Arturo are great warriors who gave their all to Juventus.
But:
- Vidal wanted to leave Juventus, went to Bayern, and after that claimed that he finally was at the big club capable of winning the CL, which was a pretty obvious insult for Juventus and Juventus fans;
- Mandzukic wanted to stay, was forced out, and after that is still thankful to the club and didn't make a single controversial claim (and never will, everyone knows it).
I like Vidal as a player, but he's definitely got that "rookie gene" in him. That's why he's not a legend, while Mario is. The big difference is hidden in small things.