read the benchmarks i listed and linked to.
that depends on what you considered "alot" worse.
in general thats the breaking point between mid level graphics (760) and high level graphics (770) settings being playable.
as for what is best for you... thats your own decision.
did you want to save some money and are willing to accept playing on lower graphics settings? if yes then the 760 works. did you want to play at higher settings and play games further into the future on higher settings? then get the 770.