604e vs. POWER3

Hello, who has experience in Linux for PowerPC on 603e and/or POWER3 processors? I am interested in performance values of these processors. I think, 604e is 32 bit and POWER3 is 64 bit. 1. What does the kernel on a POWER3 processor? Does it run in 64 bit mode? 2. In 32 bit mode, is there a great difference between the two processoes? Uwe Kiewel