How is the IIT Madras BSc Data Science and Programming course? Can it be compared with BSc Computer Science?

As you can see, both these courses are incredibly different, even if you just base it on their names.

Data science will need some knowledge of computer science but it does not completely entail computer science. It will also need you to know about machine learning, statistics, and mathematics.

Both these subjects are vastly different. With the increasing need for data scientists around the world, institutes have been compelled to provide this course be it online or offline.

My advice to you would be to do your research before you decide to enroll in either of these courses.