To be able to define what is better among software engineering and computer science depends upon an individual’s skill sets and interests. Both the careers have an acknowledgement over the vast industries.
As i am a coordinator of Data Science department, i would like to address your second question.
Data science is absolutely a very independent field in itself and is not a part of software engineering. You might get confused between the two because both of them contain programming languages as a common subject.
Data Science primarily is involved around maintaining huge data sets and deriving valuable insights in order to ensure a better functioning of the organization. It involves making crucial decisions and solving problems in real time. It is the talk of the town in the present world and is not going away from the most demanded jobs list in the near future.
To sum it all up, data science is one of its kind field and is completely different from software engineering.