it all depends, the zx4 badge wasnt offically used on the focus untill 05. all engine parts work for all focus, depending on the engine of course, regardless on being sedan or hatch. The exhaust on the sedan is slightly longer than the hatch.
as far as exterior the FRONT bumpers, hood, headlights, grill, fenders, fog lights, are all the same, most side skirts will fit all models, (exc. wagon) but some wont for the sedan, the REAR bumpers are differnt as well. and look at the years of the parts 00-04 are the same, and 05-07 are the same, some but not all, are interchangeable
the interior is the same for 00-04 as far as dash parts go, changes in 05-07, and again in 08, the front seats are all interchangable for all years of focus, the sedan rear and the hatch rear seats are not the same.
hope this helps you out, if it does not, post what particular part you are looking to buy and you will get a more percise answer