“Tacos” can use either corn or flour tortillas. The best tacos in the world (IMHO) use freshly made flour tortillas and have charcoal-cooked beef, and come from Hermosillo, Sonora, Mexico. You’re a fool if you order corn tortillas there, and even my wife (“it’s not a tortilla if it’s not made from nixtamal”) agrees that when there, flour is king. Now keep in mind I’m not talking about those awful flour tortillas in the refrigerated section from the big chain grocery store, either.
When in Creel, Chihuahua, Mexico, I ordered Tacos at a fonda. I don’t know if they were catering to American tourists or not (most of the tourists were Mexican), but it was the first time I’d ever, ever, had a “Taco Bell” style taco in Mexico, i.e., the fried (hard) corn tortilla, picadillo (seasoned ground beef), lettuce, and cheese. Maybe it’s typical for the region, but I don’t so!
In much of the rest of the country that I’ve been to, a taco is anything you put in the tortilla (unless it’s a quesadilla). For a lot of people, you make tacos from whatever dish you’re served when it’s accompanied with tortilla.
Among the people that I know in Mexico, the use of “burrito” is somewhere rare compared to “burro,” of which, of course, the former is the diminutive of the latter. In the center or the republic (say, Guanajuato), burros are much less common than tacos. In Sonora though, where tacos made with the best meat on earth reign supreme, burros are a lot more common. I imagine that it’s because in that region, “tacos” are invariably some delicious beef (or “tacos fish” which is different and distinguishes them), and so market forces drive them to sell burros/burritos with more traditional taco fillings. They’re also made with the regional, excellent flour tortillas, except in this case, often with “tortillas sobaqueras” that are arm-length in diameter.
Dang, I need to find a reason to go visit Hermosillo again. Or eat a bigger breakfast before talking about their food.