Anchos are dried poblano peppers. Wide and dark with a "raisiny" aroma.
California or Anaheim Chiles
Mild, long green chiles; available fresh and dried, but usually bought as canned chiles.
Distinctive smoky flavor. Can be purchased dried or canned in a marinade called adobo. These chiles are actually smoked jalapenos
Reputed to be one of the world's hottest. Lantern shaped, red or orange. Said to have a unique, fruity aroma (I wouldn't know); use with caution.
Named for Jalapa, the capital of Veracruz, in Mexico. Widely available, fresh, canned, pickled. Mild to hot. A staple in TexMex cooking.
Sweet, earthy flavor. Mild enough to add lots of flavor to a recipe without too much heat. When dried, they are identical in appearance to California chiles, but are hotter. Dark red, dried New Mexico chiles are the ones you see in wreaths and strings.
Poblano or Pasilla
Dark green, rather mild to medium-hot chiles, ideal for stuffing, as in Chiles Rellenos.
Small (1- to 1-1/2" long), dark green and very hot. Available more and more in supermarkets.