R3 vs rolling

I am in need for some clarification.

Although NYU has three admissions deadlines, when I met with them they said they have rolling admissions and that it would be better to submit my application when it's strongest rather than trying to make a deadline. However, I am reading the posts on here and quite a few say it will be just as difficult to get in R3 at NYU as any other school. How does NYU have deadlines and have rolling admissions at the same time?

I thought rolling admission was different than rounds because the applications are not being compared to a pool?


Thanks