Hello nimisha

Both the courses are very interesting, you can persue based on your interest and choice.
Biotechnology is the course which includes technology used in biology. Graduates can opt for technical jobs or can go for msc or PhD which will lead you to a good job.
Forensic science is a 3-year graduate course which involves the application of scientific knowledge to the investigation of crimes. Average salary starts from INR 3-5 Lacs.

All the best :)
Hope it helps :)