B. Tech is 4 year course.
M. Tech is done after btech, so to get btech + mtech it takes 4+2=6 years.
Integrated M.Tech is a 5 year course, which covers the Btech portion and then the specialization, hence you save 1 year.
you do not get a Btech degree, you get just one integrated degree.. value of which is same as btech + mtech.
studying in integrated program is not different, in first year, all the int.Mtech guys study exactly same as what btech guys study..its just that in the later years, integrated Mtech guys go for specialization in their respective branches..