What is the difference between GDR and ADR? Explain

Global Depository Receipts (GDR) They are the depository receipts denominated in US dollars issued by depository hank to which the local currency shares of a company are delivered. GDR is a negotiable instrument and can be traded freely like any other security. In the Indian context, a GDR is an instrument issued abroad by an Indian company to raise funds in some foreign currency and is listed and traded on a foreign stock exchange.
American Depository Receipts (ADR) They are the depository receipts issued by a company in the USA. ADRs are bought and sold in American markets like regular stocks. ADR is similar to a GDR except that it can be issued only to American citizens and can be listed and traded on a stock exchange of the USA.