Hii,

VIT Vellore is better than VIT Chennai for B.Tech in Computer Science. Vellore has more experienced teachers, better campus life, top companies for placement, and more student activities. Chennai is good too, with modern buildings and decent placements, but Vellore is older and more famous.

If you want more exposure, Vellore is a better choice. But both follow the same course and give the same degree.