Hi

Birla Institute of Technology and Science, Pilani is commonly known as BITS and Birla Institute of Technology, Mesra is called BIT. Admission to BITS, Pilani is through BITSAT and BIT, Mesra is through JEE Main.

For more details, check: https://engineering.careers360.com/articles/bitsat; https://www.careers360.com/university/birla-institute-of-technology-mesra.

Hope this helps.

Cheers!