Hello,Vishesh

B.Sc Computer Science with teach you only and only about computers. The subjects will be different kinds of subjects related to computers, like PHP, Java, Hardware, etc. However, B.Sc physical science has additional subjects which are physics, chemistry, maths, computer science as it's subjects. You'll have to study all of these subjects for physical science. But the plus point is that if you do a degree in physical science, you may opt for physics or computer science or mathematics, whichever you like, for an MSc degree.

Hope trhis helps.

Thank you.