The first filter is simple: ask which exam actually opens the door for your course. In Delhi NCR, CUET is the main entry exam for DU, JNU, Jamia and most other central universities. For engineering in Delhi NCR, you are looking at JEE Main / Advanced for IIT Delhi and other engineering institutes. For medicine, NEET UG is the route for AIIMS Delhi and other medical colleges.
That pattern repeats across states. Kerala uses KEAM for engineering, pharmacy and architecture. Tamil Nadu uses TNEA, which is marks-based for most engineering seats and is not a separate written test. Karnataka gives you two paths for many engineering seats: KCET for state-quota seats and COMEDK UGET for private-consortium seats. If you want the full Delhi NCR picture, including who uses CUET and what the fee bands look like, check our state guide: Delhi NCR study guide.
This matters because the right state is often the one whose admission system matches your strongest route. A student who is better at Class 12 marks may be a better fit for Tamil Nadu. A student who wants one exam to cover many central universities may prefer Delhi NCR. A student who wants a private engineering backup plan may like Karnataka or Maharashtra, where the state systems are organised around centralised counselling.


