Rumors are that while MS will have the GPU TF benefit, Sony's console will have a faster and larger SSD and faster RAM. How that will work out exactly, I'm not sure, but raw TF numbers are becoming less significant.
I'm expecting that MS Series X will be mildly more expensive than PS5, while MS Series S (or whatever the cheap option will be called) will be mildly cheaper. MS seems rather conservative by not wanting to break compatibility with even the launch X1, while Sony seems to be a bit more daring by not guaranteeing that next gen games will be playable on PS4 models.
I'm really skeptical about the BC topic. MS says it's going to be there and Sony seems hesitant but they did say all their first party titles would be. It seems like Sony doesn't want to say it will be 100% BC because they could end up being responsible for patching various games that don't work out of the box. It makes me wonder if MS is just claiming 100% BC but can't really do that because they would have to play every single game ever released on the X1 and verify it works. MS is well known for saying things that are hyperbole or just flat out wrong.
The difference is, xbox is easier to emulate, the ps3 and ps2 had very different chips, so unless the ps5 comes with a ps3 chip (extra manufacturing cost) then it wont play the ps2 and ps3 discs at all, and I fully believe the emulation will continue to be the PS Now which makes profits for Sony, PS5 will only play ps4 discs that's my bet. There's no way that sony would take the time, effort and cost of patching thousands of games, even Microsoft took years to patch hundreds of 360 games, at least Microsoft already have those patched.
Me personally Im happy with only ps4 emulation, to be honest ps2 and ps3 graphics are already very dated, and will become more so very soon, besides, theres many new good games to play, no way I'd go back, in fact Im happier if they would continue remasters, I'd rather pay for much better improved graphics and performance, and to be honest most great games were already remastered from generation 6 - Last of us, God of war 3, Uncharted collection, Bioshock collection, Batman games. In my opinion from that generation we just needed a metal gear 4 remaster, and a Mass effect trilogy remaster, but I'd be happier with a mass effect reboot instead.