What is the difference between eCompass and Compass sensor?

Today I saw a newly launched Lenovo mobile A700 which is 4G enabled.
In the specification of the sensors list I saw eCompass.

So question is that what the difference between eCompass and Compass sensor in smart phones?

Also tell me what gyroscopic sensor work for in smartphone?
Which are sensors take in account when buy a smart phone?

Is qualcomm better than mediatek processor?

Too many questions friends. Please answer them.

Thanks in advance
Agentkp. :love: :cool2: