the gtx765m is a mobile gpu where as the 780 is a desktop gpu. if you're asking about the 780m... one 780m will be better then 2x 765m... by about 10%-15%
lol, the in the world of video cards, the bigger numbers are always "better"
Explain R9 280/285/280x then 😛
For the most part, the higher number of the same serious is better. He didn't account for things like a 680 vs a 730. And as far as the 285 goes, it is a slightly different arch, and it is possible it breaks the rules, but it likely trades blows. It also lacks the 'x' at the end.