zetec started as an engine name then became a trim level name as in the galaxy 1.9 tdi zetec or mondeo tdci zetec, the focus rs mk 1 was called a duratec by ford but is actually a black top zetec.
the easy way to tell is belt driven = zetec
chain driven = duratec (which is a mazda engine and just loooooves eating piston rings!!)