Your Residency has a painted lower skirt and the color difference could be from a door getting a repaint due to a flaw at the factory or repair later at a dealership. Or it could be the painter ran out of the quart paint, refilled and had a little different "mix". In '94, most of the industry used Filon sidewall material and as Tom stated, the outer skin was a thin gelcoat film. The problem was...it had very little UV protection built in, therefore you would see one color sidewall material, another color front bumper because that was made of plastic, and another color door because that was aluminum skin. In approximately '97+ they started going with thicker gelcoat to get rid of the fiberglass "hairs" that were noticeable and have a smoother "automotive" look to the sidewall. In turn, they also added a UV protectant to reduce fading and chaulking. Today's motorhome requires no wax at all other than to make it shinny and easier to clean. PLUS...it does help add a little protection to lower skirts for rock chips.
Right around the same time, decal manufacturer's started putting a UV coating on the outside of the tapes to reduce fading, cracking and peeling and recommend NO WAX!!! as it suffocates or capsulates the tape and will actually crack or peel faster. By waxing your '94 you may cause it to fade faster by providing a magnifying glass effect if the wax does not have a UV protection, and most don't. Also, you should never wax over the decals. Check out ProtectAll for UV inhibitors and products that are recommended by the tape companies as well as fiberglass.