The other day, I was speaking with a coworker of mine who's originally from Mexico, distrito federal to be specific, and in discussing accents within Spanish I made use of the term "dialecto" the same way I would use the word "dialect" in English. She corrected me and swore up and down that the word was used strictly to refer to indigenous non-Spanish tribal languages in Mexico and Central America (or anywhere else, I suspect, but just as examples).
I've had experience with this use of the word. I've had contact with a lot of people, usually from Guatemala as best I can recall, who spoke little to no Spanish, only their own tribal language. A couple of people at work called them (the people themselves) "dialectos," but I always assumed it was a colloquialism and not technically correct. My coworker, on this occasion, insisted that the word "dialecto" did not refer to dialect the way we talk about it in English.
Any help? My smile-and-nod approach to people without any linguistic background is clashing with my deference to native speakers with respect to how their own language is used. Who is correct here?