Dunno, try here for both varieties.> Dried Chile Peppers

The flavors are somewhat different. You have to sample them yourself to see how you want to use them. I've been to Oaxaca many times and have had many chilies that I did not care for, and so I recommend that you sample them before you proceed. I do not particularly like mole and I had a very hard time finding restaurants in Oaxaca that I liked. Now there are quite a few Oaxacan restaurants here in Los Angeles, but I mostly avoid them - I prefer Yucatecan food.

You can also check Mouthfulsfood, which has a Mexican and Latin American food forum, but you would probably have to check their archives, as it appears not to be so active any more. I used to post there a lot 10 years ago.

Thanks for replies. I have been starting to suspect that Costeno and Chilhuacle are perhaps simply regional names for the same or similar varieties of peppers.

Or, that some of the seed I acquired might not be true-to-type.

My Chilhuacle Rojo fruit were very similar in size, appearance, shape, flavor as my Costeno Amarillo, the only major difference was fruit color. The Chilhuacle Rojo plant was more bush-like in growing habit while the Costeno Amarillo was obviously tree-like. Costeno Amarillo was the far more productive variety. I consider both varieties to be of marginal use, having very thin walls and tough, leathery skins. Interesting peppers, though.

To add to my confusion, my Chilhuacle Amarillo fruit were very different from my Chilhuacle Rojo and Costeno Amarillo, and much more useful and pleasant tasting. Quite decent when roasted. The plant was tree-like and a much longer-season plant than Chilhuacle Rojo or Costeno Amarillo, only got a few ripe peppers before the season ended here.

Very useful input for me. Thanks