What is the difference between the Onkyo-SC886 and the Marantz AV8003? (besides $1000.)

They are different platforms, designed and built by different companies, but that's sort of the obvious answer. They use different video processing chips (Reon for the 886, ABT for the 8003). I would have to pick through the 8003's manual to see how the two compare when it comes to making adjustments and configuring (control over video processing, bass management, etc.). The 8003 has one extra component video input, too (4 compared to 3 for the 886). And I have no idea how the analog section of the 8003 and the 886 would compare. Marantz would tend to have a better reputation, of course, but there's more to it than just reputation...