This answer can be answered in 2 aspects; branch wise and Institute wise.
Branch-wise, ECE is way ahead of Manufacturing Science and Engineering and has a wider scope after graduation. ECE students are hired by both electronics and software companies. Moreover, ECE is a major stream whereas Manufacturing is just a sub-stream under Mechanical Engineering.
Specifically talking about colleges only, I would suggest you choose IIT KGP which has a stronger brand name and legacy than BITS Pilani Hyderabad. Its reputation is not just limited to India and has great scope outside India as well. It gets better and more companies than BITS during campus placements.
One major point of difference is the location of both institutes. Hyderabad has a much superior location than IIT Kharagpur thus offering better college life and exposure. IIT KGP is remotely located and lacks the necessary industry touch and exposure.
You have to travel long distances just to eat or do shopping. You will miss out on city life and the opportunities it has to offer. While the campus is great, you have to stay inside as the world outside is desolate. Spending 4 years without much exposure might limit your opportunities.
Hyderabad on the other hand has everything city life has to offer apart from being a major IT hub. This makes it possible to apply for campus jobs as well which is not possible in the case of IIT KGP.
In the end, it’s you who has to make a decision. Go where your heart is inclined the most be it ECE or Manufacturing at IIT or BITS. Just make sure to make a decision that will not make you regret it later.