hardware wise the R7 250 is inferior, and based off of the 7730 which is a 7750 but with some limbs cut off
i read a review said that R7 250 is better bec. it have AMD Stream Technology,AMD Avivo HD,Mantle,DirectX® 11.2,OpenGL 4.3, and TriXX Utility that HD 7750 don't have is that true ??
Actually, the 7750 has most of those, it doesn't have trixx or trueaudio IIRC, but everything else it has, most of those are features that software programmers can support, but it depends mostly on the developers/programmers and not what the card has, if no software even uses these features then they're useless.
I believe the HD7750 has support for only 4.2 OpenGL acceleration and that's the only difference for the features that matter (it's not even much of a difference)