capital / capitol
The city, the money, the uppercase letter, and the death-penalty adjective versus the building.
Capital is the city that houses the government, the money invested, and an uppercase letter: capital city, raise capital, capital letter. It is also the adjective for a crime punishable by death: capital punishment, a capital crime. Capitol is the building. Capitalize Capitol for the building in Washington and for a state’s capitol when you mean that building.
Examples
UseAustin is the capital.
Usecapital punishment
UseThey met on the steps of the Capitol.
AvoidAustin is the capitol.