I know this is a pretty old thread, but I think I have the answer to your question. What everybody says is absolutely correct, the names for beans (just as for most foods, especially fruits) are a total mess with a lot of regional variation. However, going to your original question of why you saw the variation at the supermarket: I bet you came across this variation with the Goya brand of beans. The reason for the use of habichuela for most of their beans is that Goya is historically heavily associated with Puerto Rico, where the term is used. Goya was founded by a Spaniard (in Spain they also use the term in some regions), who emigrated to Puerto Rico and then emigrated to New York (heavily Puerto Rican) and founded the company. The company is headquartered in New Jersey (also heavily Puerto Rican). There is also an important manufacturing center for Goya in Puerto Rico. However, Goya names their black beans frijoles (and I think those are the only one they call frijoles, if I'm not mistaken). Black beans are not really used in Puerto Rican cuisine, but they are in Cuban cuisine, where they call beans frijoles. There is also an important manufacturing center in Miami (heavily Cuban), hence the occasional use of frijoles. I haven't seen any other brand of beans that use habichuela in the US. Mexican beans, Brazilian beans, and others all use frijoles in Spanish, at least the brands sold in the US, and California, specifically.



I hope this somewhat helps in answering your question about your supermarket experience, or at least shed some light on it.