LENOVO S650 VS LENOVO S820?

Could you help me to decide which one should i buy. I'm really confused. The s650 is cheaper compared to s820 because s820 has a 720p screen resolution, but when i checkout antutu benchmark s650 has a score of 17000-18000points where else s820 has 13000-14000 points. I'm really confused. S650 has a mali-400mp2 gpu and in s820 you get a powervr sgx544. Which is better?

Can you give us more info?