Of course autopista is a highway, motorway, or turnpike. And pista can also refer to a racecourse. Just a plain (paved) road is a carretera. Ruben says that a camino connotes an unpaved or "unimproved" road. So some might think that is a trail. Also sendero is used for trail, as in "hiking trail", more narrow and rugged than a camino.

Chuck, it can all be so confusing