Well if you are only interested in south NITs, I assume you mean Trichy, Warangal and Surathkal.

In these three NITs you can only get lower streams like Materials Science and Metallurgy, Biotechnology, Chemical Engineering, Mining Engineering etc.

In NIT Calicut you can get Civil Engineering, Bio-Technology, Chemical Engineering, Production Engineering and maybe even Engineering Physics.

If you want NIT Puducherry or NIT Andhra Pradesh then maybe you can get any branch of your choice.