Categories are assigned only on the basis of your VITEEE rank. The difference is only in the tuition fees whereas the hostel and mess fees is same for all categories.
Category 1: rank 1 to 20k.
Tuition fees: 1.98lacs
Category 2: rank 20k to 50k
Tuition fees: 2.5 lacs
Category 3: rank 50k to 65k
Tuition fees: 3.25 lacs
Category 4: rank 65k to 80k
Tuition fees: 4 lacs