Throughout India, different music systems or styles can be found. However all of them can be broadly classified under two main systems: Hindustani and Carnatic.
In olden days, Carnatic Padhati (system) was common in Mysore, Andhra Pradesh and Madras. Since this style originated in the region of Karnataka, it was named Carnatic Music. It is also known as South Indian Padhati. Hindustani Padhati was popular in rest of India. It originated in northern India.
Both these widely popular systems of music are independent of each other. Although there are independent, they are many similarities between them . It is believed that in ancient times they were not separate. Throughout India there was a single music system. However with time, these 2 branches were formed. Even today, both the systems have only 12 swars in each octave (saptak). Both the systems strictly adher to the rules of thaat and ragas. Therefore, both are different but similar at the same time.