Ok then let's do it another way.
For $400 and $400 only, you can have access to the all the media functionality of the all in one media solution of PS4 as well as having access to 4 games.
For $500 and only $500, you have a box with no playable games and no media functionality on XBO. Where is the $500 "all in one entertainment system"?
For $500 plus tax, you have a box that without spending more money can't do a damned thing.
I think they are counting on a few things to make it worth that extra $100
1. Better Games - Most important, comes down to personal preference but Microsoft has hit here with me.
2. A 'Next Gen' Feel - XB1's user interface and interaction seems far more advanced than PS4, partly due to Kinect. These features will get some 'wows' from casuals and people that see PS4 as more of the same, just more powerful
3. Entertainment - I am still fairly convinced they haven't played their hand here yet. Either they won't have much for launch or they are still more announcements to be made. Right now they have not made a compelling argument for how XB1 is better for entertainment than PS4 IMO. We don't know their apps, services, or partnerships.