Saute is high heat, little fat. Sauteed food is typically allowed to brown, at least slightly before moving it in the pan. Sauteing cooks the food mostly with transferring heat from the pan, through a process called "contact conduction."
Stir fry is also high heat, but more fat. Because the food is cooking in oil, it can be moved around without altering the browining process (Maillard reaction, usually). So, typically there's more agitation to insure the food cooks evenly. Also, the ideal pan is different -- for stiry frying that is a wok. A wok allows the cook to move food through a depth of oil, without leaving it there for a few minutes. While contact conduction plays a role, the physics of stir frying is much more dependent on liquid immersion conduction.
http://www.cheftalk.com/t/44180/saute-vs-stir-fryHaving said this Spanish does not really have this difference and you saltear both in a sarten and a wok so I think the best option is stir fry (after looking at images of the dish)