Hello student

hope you are doing great. As per your query  I would glad to inform  you that data science is not a stream ,it is subfield of computer science(kind of specialization) . Degrees are mostly done in streams where subjects are data science ,AI are taught so that student can have muitple options to adopt in carreir . In online data science course,they mainly focus on data science only so the duration is short but the sylllabus is same ,infact online course makes your fundamentals very strong

Hope you found this answer helpful. Good luck for your future