Capital as a noun refers to the first city of a State or a country.
It also means: hub; center; headquarters.
Capitol refers to the building where the administrative body of the government (Legislature) meets.
1. New Delhi is the capital of India.
2. The Pin Valley National Park is located in Shimla, the capital city of Himachal Pradesh.
1. The American President requested the heads of the Army, Navy and Air force to meet him at the Capitol in Washington, D.C.
2. The local Municipal Corporation’s office was easy to locate, as it was near the Capitol.