Are there overlays showing the difference between how coal is dispersed on the planet versus oil? What about showing the varying depths and thicknesses of these deposits relative to each other?
Not playing around are you??? Have you checked the US geological survey.
Here's a couple of maps you might be interested. You'll need a big monitor or a lot of patience to view these.
You can also browse their energy section in general which is full of information on coal, petroleum, and a lot of other stuff.
You can find some very general maps displaying oil and coal distributions, but I'm not sure how accurate they are.
Are there areas of the planet that are known to be free of fossil fuels? Are there maps that show known areas that are void of deposits?
Off the top of my head, I know that the Canadian shield is totally void of hydrocarbon resources. Most of Western Australia and Western China as well.