NITs (National Institutes of Technology) and IITs (Indian Institutes of Technology) are both premier engineering institutions in India.
The main differences between NITs and IITs are based on:
Admission process: Admission to NITs is based on the marks obtained in JEE Main examination while admission to IITs is based on the marks obtained in JEE Advance examination.
Course offerings: NITs offer only undergraduate and postgraduate programs based in engineering and technology while IITs offer various disciplines with more specialization in tech courses.
Funding: IITs receive more funding than NITs from the government for research and development activities.
Placements: IITs have a higher placement rate than NITs with companies offering attractive packages.
Ranking: IITs are ranked much higher than NITs by various ranking agencies like NIRF, Times Higher Education and QS.
Ultimately, both NITs and IITs provide premier engineering education in India. It just depends on your preferences and interest areas about which one you want to opt for. If you are more inclined towards an intensive research atmosphere, then IITs can be better suited for you, but if your goal is to gain a degree in specialized engineering course, then an NIT could be the perfect choice.
Hope this answers your question.
Good luck!