M-Powered is made specifically M-Audio I believe, as far as what they can do I think it is nearly the same.
Basically, there are now visible differences between 800 and 803, except some critical issue fixes related with stable work.
Price.
the difference between a pro and a con is that a pro is the good thing and a con is the bad thing about htte problem.
Yes, although you will need an M-Audio interface connected to the computer in order to launch ProTools MPowered, or an Avid audio interface connected if you plan to run ProTools LE versions 8 or earlier.
the letters after pro
the 026 pro is a newer version
Yanga
Neither is as good as the full version, but from those two - Pro Tools MP9
Mbox 2 Pro has more inputs.
pro has bigger memory and 3 mp camera.
sample rate difference. they have to be set to the same sample rate
There is no Pro Tools LE 9.