Hi pal,

Bsc it , is a Bachelor's degree awarded for an undergraduate course or program in the Information technology field. The degree is normally required in order to work in the Information technology industry.

B.Sc. Computer Science is 3 year ug program which deals with subjects and topics related to computer application and services.Technological implementation of computer systems is the main agenda of the program.

Bca,  This course provides a sound academic base to students to help them pursue advanced career in computer application and information technology. It is an ideal course for the students who want to make career in computer science and related fields.

So here bca combines both it and cs.but here choice is yours what you wanted to do. Each field have it's own uniqueness.

Hope this will help you.

Good luck.