Is syllabus for M.Tech in aerospace engineering related to mechanical or is it different? I am B.Tech in mechanical.

I want to do a job in companies like DRDO, HAL, Boeing, etc. but I'm a bit confused about it. So, please advise me if it is right to do M.Tech from IIT in aerospace or mechanical? Which specialisation should I go for? My dream is to study in IIT as it provides great practical knowledge.