Photoshop has a much more extensive range of features. IMO you shouldn't really be comparing these two though... Fireworks is more a counterpart of ImageReady, which also serves to prepare web graphics.
I use Photoshop, as I think that one of the best features of fireworks, is that it "makes your code". The code usually is pretty bad, so I havejust sticked with PS.
Both. I use photoshop and fireworks, but i tend to use potoshop more.They're not too different, but i think firework's user interface is much better (macromedia's interfaces are awesome in my opinion) and fireworks has a faster learning process.Don't really prefer fireworks or photoshop, tough.