Without any second thoughts, choose BSc Data Science from IIT Madras. Upgrad course is just an additional course between you and your degree from IIT Madras. 

Choosing BSc program from IIT Madras will offer many perks 

• You become a part of the extensive alumni network of IIT Madras
• You will be able to avail of Institute placements 
• Fee waived based on your income criteria 
• You can clear your doubt directly from the IIT Madras faculty. They are highly approachable.
• Weekly evaluation maintains the quality standards of the course and makes it one of the best Distance Education Programs.
• The online course from Upgrad awards you just a certificate while that from IIT Madras awards you a degree.
• The exams of Upgrad are conducted online whereas BSc exams are conducted offline at exam centers highly under the surveillance of examiners.
• There is a fixed duration (3-4) of the BSc program which is absent in the case of the Upgrad course.
• Your CV will be bestowed with an IIT tag, known worldwide while the Upgrad course is rarely known outside India.
• Internship opportunities are available under the BSc course thus offering much more exposure than Upgrad where you are expected to be already employed.

Upgrad is suitable only for those who are working full-time and cannot pursue a full-time course. Else, BSc should be your first option. This course can be pursued full-time and gives enough time to prepare simultaneously for many things like the Civil services exam, and CAT exam or inculcating skills like drawing, painting, music, etc.