What is the difference between 4 year and 5 year programs at iit?

Hello,
4-year programmes at IIT are the 4-year B.tech programmes offered in various engineering streams like Computer science and engineering, Electrical engineering,  Civil engineering, Mechanical engineering, Electronics and communication engineering, Chemical engineering, Engineering Physics, Metallurgical Engineering etc. 4-year B.S. programmes are also offered in various subjects like Mathematics, Chemistry and Economics. 5-year B.tech+M.tech programmes are also offered, like Electrical Engineering with M.tech in Communications and Signal Processing, Electrical engineering with M.tech in Microelectronics, Mechanical engineering and M.tech in Computer Integrated Manufacturing etc. Admissions in these branches in IITs are based on JEE Advanced ranks.
I hope this helps.