Green Chile is a mild member of the pepper family, hotter than a bell pepper but not as hot as a jalapeno. There's your standard green chile, and then there's the stuff grown and sold in Hatch, New Mexico.
Like those onions that are grown in a certain part of Georgia, the green chile from hatch is entirely different from the regular stuff. It has a deep, earthy flavor that's drawn out when it's fire roasted. Folks say it's the climate and the soil.
Hatch's chile isn't an entirely obscure taste. Every year people from the world over flood the tiny New Mexico hamlet for the annual chile festival. Yes, it's that damn good of a pepper.