Selection of the course is totally depends on your interest and calibre. You can opt for M.Tech to get in-depth knowledge of your current field. You can opt for M.S if you want to go abroad for your studies.
If you want to pursue M.Tech, then you need to appear for GATE Exam for getting a good college. Graduate Aptitude Test in Engineering (GATE) is an all India examination administered and conducted jointly by the Indian Institute of Science (IISc) and seven Indian Institutes of Technology (IITs) on behalf of the National Coordination Board - GATE, Department of Higher Education, Ministry of Human Resource Development (MHRD), Government of India, for admission to Post Graduation/PhD courses in Engineering and Architecture.
If you want to go abroad for M.S then you need to appear for English proficiency Test i.e. IELTS or TOEFL to go for study abroad. You also need to appear for GRE Exam to pursue engineering in abroad. You have to contact to abroad univesrities individually for internship related details.
Graduate Record Examination (GRE) is a standardized test that is required to be taken by students seeking admission in any of the graduate schools. Students seeking admission into any Masters Program (Master of Arts or MS) in US, and many other European countries as well are required to take GRE.
Both the options are good and have different values and scope. It is advisable to select any of these courses according to your interest and abilties.