I really liked the Gantz anime. It was crazy, a mind trip, and overall an enjoyable (if somewhat graphic) show. But I've been told the manga is better, and goes in a wildly different direction. What episodes in Gantz are based off the manga plot, and where does the plot truly start to branch?
Note, I'm not looking for minor differences, though bonus points for noting those. I'm really looking for when the major branching in plot occurs.