In general both cuda cores and stream processor are the same thing. Those two were the many cores that doing parallel stuff in gpu. (Nvidia also called their cuda cores as stream processor in the past). The difference is both were built on different architecture hence the performance of the two can't be directly compared based on their core count.
oasis51 :
But when it comes to performance usually 770 will outperform 280x slightly...
different architecture..
nvidia is slightly better for optimize their configuration lead to better perfomance..
and, gamedebate is not reliable..