Hello

BTech is a course you can do after your 12th. It is a four year course. MSc in CS is done after BSc i CS and it is a 2 year course.

To do MSc you will need 5 years whereas for BTech you will need 4 years.

Now coming to the scope you can become Software Engineer or developer, System Engineer, Database Administrator, Web and Mobility Engineer etc. It is a high paying corse specially if you get enrolled in a prestigious institute like IITs or NITs. It is a very good option and the average payment after just the 4 year course will be around 5 to 6 lpa and higher if done from a good place.

MSc CS- You can wor as a scientist or technician or researcher or teacher or developer or IT consultant or Software engineer/ IT Admin/ Network engineer etc in many eminent places like National Institute of Electronics & Information Technology (NIELIT) , Airpost Authority fo India (AAI) , BECIL , Banks , Colleges and Schools. The package depends on skills but it is for sure that you will not be jobless and will probably earn around 6 lpa (depending on the job).