There are actually 4 restaurants in Epcot's Mexico.
You are booked at the San Angel Inn restaurant. It's the one inside the pavilion, has existed since the park opened, and is on the waterfront of the boatride.
There is also a tequila bar that opened recently, La Cava del Tequila. It replaced a bit of retail inside the main pavilion. It has tons of types of tequila and serves light appetizers.
Then there is the Hacienda de San Angel and the Cantina de San Angel. These two locations are set to open soon on the waterfront of the main park promenade. Hacienda will be table service just for dinner. The Cantina used to exist all by itself in the same location, but was closed when they rennovated extensively and built-on to allow for both to exist. It will reopen and likely serve the same tacos, nachos, etc.. it always had before.
So, 4 locations, 3 are named "San Angel" in some format.