The CS engineering programme usually deals with how to build micro processors, how to write a compiler etc. IT is the business side of computers - usually dealing with databases, business, and accounting. One way to think of it is that IT deals with the application of computing technology to real life processes and CSE deals with the “science” that facilitates these applications whereas wise and strategic use of computers (information system) gives businesses a competitive advantage and helps government agencies and non-profits serve clients efficiently and well. Computer-based information systems have become critical to most organizations, and the strategy surrounding them is integral to any organization's broader strategy.

Hope this helps!!!