Hi,

Cutoff rank is the rank at which the last seat of a course is filled. The cutoff depend on many factor like number of seats available, total number of candidate applied for a course, percentile obtained by candidate who applied for a seat in that course. That's why if you look at 3-4 years cutoff you have found that it varies from year to year.

Among the candidate applied for a course in a college all the seats are filled according to rank/merit in jee exam.

Hope you understood.