Anaheim
C. annuum L.
New Mexican type
Ancho / Poblano
C. annuum L.
Poblano type
One of the main chile peppers used as pepper powder, together with mulato and pasilla, the main chile pepper used for moles. Mild to quite pungent, but especially noticable through its sweet aroma, particularly in dried form. The dry peppers are brick-red to black-red; fresh ones a bright red. Spoken strictly, "poblano" means the fresh fruits, "ancho" the dried ones.
Guajillo
C. annuum L.
New Mexican (or, according to Mark Miller, Cayenne)
mid to tall plants, good producer; very common chile pepper in Mexico, used dried in ristras und with various dishes; medium pungency
Habanero, Orange
C. chinense Jacqu.
Orange Habanero
Usually associated with the Caribbean, habaneros tend to be easier to find in Mexico. Very high pungency, fruity-tropical flavor
Jalapeño
C. annuum L.Jalapeño
Presumably, the best known of all Mexican chile peppers. In fact, "chile pepper" in brine, in the supermarket, is usually Jalapeño. Medium pungency, typical shape; either with or without (vertical) cork stripes on the skin (they are little popular with many consumers, but typical for some landraces which are considered particularly good)
Mulato
C. annuum L.
Poblano type
Along with Pasilla, one of those Mexican varieties which ripen to a black color. Even the unripe fruits have a very dark green color which is close to being black (putting an unripe and a ripe fruit next to each other, it becomes noticeable that their sheen is different); one of the main varieties used in moles, and also used in soups and salsas. Mild to somewhat pungent
Pasilla (Chilaca)
C. annuum L.
Pasilla
The second variety ripening to black, the third part of the traditional "trinity" of peppers used in moles, together with Ancho and Mulato. Plants grow very tall; pods pretty long. Medium pungency
Serrano
C. annuum L.
Serrano type
One of the varieties used the most, especially in its fresh, green form. The ripe, red pods are also somewhat sweet; both ripe and unripe, they have an interesting, clear pungency. Not very tall plants, but usually produce well even when conditions are quite bad (and then, with the pods unable to ripe, that Serrano is commonly used green is an advantage)
ChiliCult.com - Chile Peppers and Culture