NEST is easy if you have strong command on basics. But when compared to IISER, NEST is a bit difficult.

Yes, in NISER integrated MSc course is offered. NISER is dedicated to undergraduate and graduate education and research only. It offers a five-year integrated MSc as well as PhD degrees in pure and applied sciences. Degrees at NISER will be awarded by the Homi Bhabha National Institute (HBNI), a deemed-to-be University within the Department of Atomic Energy.

IISER does not provided Integrated course in MSc. All IISERs provide BS-MS programme. The programme is provided such that you should study biology, chemistry, physics, mathematics and a little humanities for first three years.