Masa Harina is a common term, so common that the peculiarity of literal meaning is subservient to the common usage. Masa harina is essentially saying "dough flour." I suspect it's a very old term among people who didn't see wheat flour, so their dough was always corn. So harina de maiz is just corn flour. same as masa harina. More than that, it's flour of corn that's been treated with lime water as for hominy, the process that improves the nutrient value and prevents the pelagra that afflicts people who live on untreated corn. The single word, masa, in the Southwest, is taken to mean the flour. Corn tortillas can be made from either the course of the fine, but the fine is most often used in tortillas and the course, which is closer to corn meal, in commercial tortilla chips, crisp taco shells, casseroles, and such where more substance is desired.
Nothing like a fresh corn tortilla just off the griddle lubricated with lard.
"Kitchen duty is awarded only to those of manifest excellence..." - The Master, Dogen