It uses the same rendering engine (Presto); it's a newer version however: 2.5 versus 2.2 in Opera 10.0/10.1.
I posted a lot of details in an earlier thread...
Opera has decided to finish the Windows version before finishing 10.5 on other platforms however they mentioned that this was an exception rather then a rule.
It's pretty solid though I would have also liked to see CSS3 multi-column support, maybe in 11. Still it's a massive update to Opera. :)