Chinaski was the Bukowski persona... but sometimes the real Bukowski played the Chinaski persona. it's a thin line, but there are certainly quite a few differences. no time to explain them now, though.
you may want to know that the earliest incarnation of the Bukowski persona wasn't Chinaski, but Chelaski. You can see that somewhere in the Unpublished & Uncollected forum.
I think there might have been another "-aski" between Chelaski and Chinaski too...can't put my finger on it at the moment, but I remember something. Maybe it was Chelaski and I'm just losing my mind...could be.
By that I mean Bukowski was, for the most part, a responsible, hard working guy. And there were definitely things that frightened him. Chinaski is (again, for the most part) a fearless bum, pissing on the world without regard to consequences.
That's a generalization, but I think it's not far off the mark.