Hi Vikram

First please know the difference between both the programmes, then decide which one is best for you.

GME or Graduate Marine Engineering is a 1-year programme. You become eligible for this programme if you do B.Tech in Mechanical or Naval Architecture. 

Whereas, B.Tech in Marine Engineering will be a 4 years programme.

So, by pursuing B.Tech in Marine Engineering, you can work in that industry only. However, if you pursue GME with a mechanical background, you can work in that field too.

Think wisely basing your interest in the field.

Hope this helps.

All the best!