It's becoming increasingly difficult to tell the difference between the freewheeling, cocky, oft-caddish Adrian Grenier and the freewheeling, cocky, oft-caddish Vincent Chase, his character on HBO's Entourage. Wednesday night in Manhattan, amid hordes of screaming girls the actor has likely slept with (it is, after all, now the next day), HBO premiered the show's fifth season at the Ziegfeld Theatre, and were it not for his publicist eventually dragging him toward reporters, we might not have heard him flub his way through some nonsensical comments that discern the actor from the character.