Omelets are (vaguely) the same size and shape as tortillas, but omelets are made from eggs, which tortillas aren’t (as far as I know).
I forgot to add that here’s the Wikipedia entry on omelets:
Spanish tortillas, not Mexican. It’s in your first link. You yourself say it’s the Spanish word for omelet.
Specifically, “tortilla espanol” is a popular and typical dish, often served as tapas, made from eggs, potatoes, and onions. Yum yum. To prepare at home:
cut potatoes and onions into half-discs and cook as for home fries in a small cast iron pan with plenty of butter or olive oil. When completely cooked and ready to serve, pour 4-6 scrambled eggs over all. Cook without stirring until the edges look cooked (but the center is still runny), then fire briefly under a broiler so the top is browned. Remove from oven, cool for several minutes, invert onto a plate, and cut into wedges. Serve hot or cold.
Wendell - here’s a link about Spanish tortillas, which describes a Spanish tortilla as the best of all omelets.
http://www.taunton.com/finecooking/articles/how-to/spanish-tortilla.aspx
Susan