Hi, basics are the same. However RGIPT shows a preference to Petroleum  refining and natural gas etc. Check the syllabus for IIT Bombay here http://www.che.iitb.ac.in/academics/UGDD07-curr.pdf and check that of RGIPT here http://www.rgipt.ac.in/pdf/placement_15jan2014.pdf. What you should understand is the RGIPT was set up exclusively for catering to growing requirements of the Petroleum & Energy sector. It is a national institute of importance equal to an IIT. the course is specialized and oriented towards petroleum refining, oil and gas products etc while the IIT and NIT courses are general in nature.

Rajiv Gandhi Institute of Petroleum Technology is a average college only.

You should try to get admision in top NITs and IITs for chemical engineering as they provide very good faculty, exposure and placements. You should always prefer a college which provides good placements.

You can check the top colleges for chemical engineering below

IITs

IIT Kanpur

IIT Roorkee

IIT BHU

IIT Gandhi Nagar

IIT Bombay

NITs

NIT Agartala

NIT Calicut

NIT Durgapur

NIT Raipur

NIT Rourkela

Good Luck!!