In a core CSE branch, you will get to learn a bit of everything within the boundaries of the branch whereas in a specialization course, a particular sub-branch is focused. That sub-branch will be the main focus of your 4 years of engineering. If you know that you are really good in that particular sub-branch or you have interest in it then you can go ahead with it.

So, CSE in Information Security deal with security issues related to data transfer across networks and CSE in Bioinformatics students do not study Embedded Systems, Microprocessors, Graphics and Multimedia, Mobile Computing, 2 math subjects and there are separate courses for Computer Architecture and Organisation and Digital Logic whereas bioinformatics students study it as 1 subject.