Aarthi, NEET is the entrance examination for admission to Medical,Dental, Ayush and Veterinary courses across India. Now NEET is also mandatory to study MBBS abroad. This is the requisite for you as an Indian Citizen to study MBBS abroad. And MCAT is a requisite by countries like Australia, Canada, US etc to check your readiness and knowledge to study Medicine in their country. It is their requisite. So you have to appear for both NEET and MCAT.