Hi ranjana,

The basic difference between M. Tech and MS lies in the orientation and course approach. M. Tech is a ckurse program whereas MS is a research program. M. Tech is a more detailed course with a lot of study required. Whereas in  M. Tech, one has to attend regular classes in order to gain knowledge of the subject. 

M. Tech degree generally ends in 2 yrs where project and study both have to be completed in that particular span of time and MS degree can be stretched uo to 3 to 4 yrs till one doesn't complete the project.

Mostly people prefer MS from USA as MS degree in the US is highly recognized and accepted throughout the world due to their academic excellence. Doing MS in USA is a great option for the research oriented and seeks a practical exposure unlike India where theoretical aspect is more emphasized.

Thank you