Default Question regarding full hd playback

I had a question regarding the full hd playback on xperia devices.
Samsung galaxy s2 has full hd playback while xperia m does not have full hd playback.
Xperia m has much better hardware than the galaxy s2.
Also antutu benchmark scores of xperia m are much higher than the galaxy s2.
Then, why does xperia m does not have a full hd playback while galaxy s2 has full hd playback.
What is it that restricting full hd playback in xperia m?