Are parmesan and Parmigiano-Reggiano the same thing?

Parmigiano-Reggiano is the legally protected name for cheese made in the Italian regions of Emilia-Romagna and Lombardia from grass fed cow's milk that is processed and aged in a very specific way.

"Parmesan", on the other hand, is a name given to cheeses made outside the region whose flavor and texture are meant to be similar to Parmiagiano-Reggiano.

Recipe: Melon and Prosciutto Salad with Parmigiano-Reggiano