An Apostille is a form of authentication issued for documents used in countries that have adopted the Hague Convention of 1961. An Authentication is issued for countries that have not adopted the Hague Convention of 1961. The Office of the Indiana Secretary of State provides an Apostille and authentication services to U.S. citizens and foreign nationals for documents used overseas.
Adiitional information and requirements can be found here: https://www.in.gov/sos/business/4096.htm