Not sure as it seems a bit more convoluted to get under the hood(or maybe its me being lazy??).
AFAIK,according to the official blurb Win8 has significant changes.
I heard Windows 7 runs away in fear when Win8(who wants those stupid "doz" its all about the tiles man) is in the same room. I was running Win8 in a VM so my Windows 7 installation felt much safer.
On a ever so slightly serious note,since I ran it in a VM I cannot make any direct comparisons to Windows 7 with regards to speed. It did install quickly though.