As a carriage builder myself, it looks like there are two different woods. This is VERY common. It would be
uncommon to use the same wood throughout. Generally, the wheels and shafts are made from hickory. There is A LOT of variation in that wood. I have seen wheels with different "colored" spokes on the same wheel. The heartwood will be much lighter than the outer portions of the same log. The reason they are built of hickory is that it breaks "cleaner" than oak, which tends to splinter more. You want your shafts made of that wood because they are next to the horse. Same for wheels. It is a very tough wood, and also takes well to steam bending, like on the felloes (wood rims) and shafts. If it is NOT hickory, then I would definitely send it back. Using hickory is a "given" for carriage builders. I don't know of any builder that would make those parts out of anything else.
The dash and floorboards look to be of oak. My guess is maybe a red oak. Of course they are not going to look the same, especially with just a protective finish (poly or spar urethane, or varnish) and not stained. Carriage builders tend to save their hickory for the other parts like I mentioned, so again this is common.
We bought a meadowbrook once, and again the wheels and shafts were of hickory, and the floorboards, seat, etc. were ash. It was a
very light cart, because ash is a lighter weight wood. And yes, it had a different look to the different woods. All of the rest of the "natural finish" (not painted) carts we build all have the same variation, but we tend to stain ours and might use more stain on the shafts than the box so that the "color" is more uniform.
If the Jerald is more uniform, it's probably because there is less wood on it. Usually, there is no wood dash or spares box. It is probably easier to find wood that will "match" the shafts and wheels, unless they actually used hickory on the floorboards. At least the builder did use the same wood on the box here, and not white oak on parts and red on others, etc.
If around $1K is all you paid, I wouldn't stress out too much. I don't mean to insult you, but if you wanted it to totally match, that would include mixing stains, which is going to cost you more. Besides, (good) judges understand that there will be a difference in the woods and the "colors". Also remember that your wood is going to "age" giving you a bit of a different look in the future. If it is polyurethaned, you may need to have to redo the finish in 3-5 years anyway, so then you can have it stained if you want.
Myrna