Aeronautical Engineering

Hello,
Pursuing Aerospace Engineering as a specialization in Post Graduation (M.Tech) is indeed a better choice. Aerospace Engineering is a niche branch in India with limited job opportunities at present. However, since you already have completed Bachelors in Mechanical degree, you can apply for jobs in mechanical sector, whilst you can also keep looking for jobs in your desired role in Aerospace Engineering. This way, your career won't halt. While, your job in mechanical domain will keep earning you experience, you can choose your path in the Aerospace domain whenever you get a good opportunity.
I hope this answers your question to your satisfaction. If you have any further questions, kindly revert.

Hello Prashant,
I understand and appreciate your interest in pursuing courses related to aviation. B.Sc in Aviation is a more theoretical course with lesser focus on the practical aspects. B.Sc. in Aviation is a 3 years long Undergraduate Degree program. This course covers topics such as Air Regulations, Navigation, Meteorology, Aircraft and Engine, Air Traffic Control, Aviation Security, Flight Safety and Crew Management. After pursuing this course, successful candidates may take up jobs such as Air Traffic Controller, Ground operations staff, Cargo management staff, Ticketing staff etc.
One may also go for PG courses related to Aviation sector, such as MBA (relevant), M.Sc. Aviation Safety, PG Diploma courses (relevant) etc. If interested, successful candidates may also go for CPL training!
Aeronautical engineering, on the other hand, has a far more focus on the practical aspects. Once you complete Aeronautical Engineering, you can work in job profiles like research and development, testing, parts assembly and/or the maintenance of aircraft or missiles. Some aeronautic engineers specialise in studying the effects of aircraft on the environment, the potential dangers of new aircraft technologies or fuel efficiency. Within aeronautical engineering, a person may focus on the design of aircraft systems, also called avionics, or materials research and selection.
It depends on your interest whether to choose Aeronautical Engineering or b.Sc. Aviation. If you are interested in Teaching jobs, go for B.Sc. in Aviation. If you want a major job role in Aeronautical industry in the profiles mentioned above, opt Aeronautical Engineering.
I hope this answers your question to your satisfaction. If so, kindly upvote this answer. If you have any further questions, kindly revert.