Equus and caballus both mean “horse” in Latin; the caballus is to distinguish it as a subspecies of Equus ferus, though I don’t know why we didn’t slap on a domesticus or a familiaris or something instead of another word for the same thing (though I am told equus and caballus are not synonyms). The point is, it’s a horse, and not the Przewalski’s horse, that’s Equus ferus przewalskii.

Find more scientific names and what they mean here and here.