Header panel is the big plastic part that attaches forward of the fenders. I don't think you'll find any appreciable difference between header panels or lights and bezels. The one thing that definitely does differ, though, is the grille. Earlier models had the grille and surround in separate pieces, and the later one has a one piece grill. All this means is that you'll need the whole grille assembly. I'm not sure, but there may be a difference in the drilling of the header panel between the two, but this should not cause any problem if you get the grille and header panel for the same year. If there's any difference in headlight bezels, it's also going to be just a matter of how they attach with the grille, and it should work fine as long as you get the whole thing.
I've swapped at least some of the parts between an 89 and a 93, but I can't remember whether that included headlight bezels. I don't recall seeing a difference. The parking lights definitely interchange, as do fenders and bumpers.