The difference is that B.tech is is all about engineering, while BCA is about application. And B.Tech is more job focused while a BCA is a good platform for higher studies.

It depends upon which course you are interested in because BSc with any specialization or general and BCA is specific to computer applications.

So in generic, you can opt for computers if you have interest in it or else go for Bsc in Computer science as well.

Good luck.