I don't deem it right to compare the two colleges directly as the alumni would feel offended and this might even result in rivalry. It's true that every college has its own unique strengths as well as weaknesses.
Ultimately, there is no ‘better’ college as it all depends on your individual preferences.
I have a few friends who have completed their B.tech from IIT (ISM) Dhanbad and Jadavpur University. Here are some crucial factors you must take into account to understand the difference.
By no means a state-level university can outstand a national-level Institute. IIT (ISM) Dhanbad has an edge over JU in almost all aspects. If you score well enough for IIT (ISM) Dhanbad, there’s no point in thinking about Jadavpur University.