IIT

IITs are the most sought after technical Institutes in India with international fame and brand. Students for IIT are selected on the basis of JEE Advanced. Legacy, IITs have the world class faculty, facilities and infrastructure. As best of Indian talent gets admission in IIT their placements is the best.
NITs were earlier known as Regional Engineering College. Though not as good as IITs, they are also excellent institutes for engineering. NITs select students based on JEE Main. It is the second best option after IITs for engineering education. You may refer to following link for ranking for IITs and NITs subject wise:
https://www.shiksha.com/top-engineering-colleges-in-india-rankingpage-44-2-0-0-0

All the IITs and IISc Bangalore jointly conduct an entrance exam, namely IIT-JAM
(I.e. Joint Admission Test for M.Sc.)
for admission in M.Sc. courses in these institutions.
The educational qualification required for the entrance exam, is B.Sc. or equivalent in
relevant discipline with following mentioned percentage of marks.
For admission in IISc Bangalore
Students of GEN/OBC category should have at least first class in Graduation and
students of SC/ST category should have at least 50% marks.
For admission in IIT campuses
Students of GEN/OBC category should have at least 55% in Graduation and
students of SC/ST category should have at least 50% marks.
This year the application process for the entrance exam has been closed.
You can apply for the exam in coming years if you do satisfy the eligibility criteria.