The main difference will be the power made under the area of the curve which can be seen on a dyno chart; Turbo's generally have a broader area if you are comparing this to a vortech s/c. Turbo sizing is also a variable that will effect the power characteristics @ 7psi.
I've rode in both setups. The power delivery on a vortech s/c setup feels more linearly while in the turbo setup, it has a nice 'torquey' feeling once boost kicks in. I have yet to ride in a Positive Displacement (or twin screw) s/c setup, however it will probably feel like the turbo setup but with no lag.
-=Slow In Fast Out=-