Here's about the first thing I found on Google Images or whatever it's called.
There's really quite a color difference between Maple and Mahogany.
Of course, under a wrap/glue, the wood won't be looking as clean as this, but you get the idea. This particular picture of Mahogany seems a bit dark to me, but in general, there's still quite a difference in the unfinished woods.
Also, the texture/grain (not sure if that's the right word) is different when comparing Maple with Mahogany.
On the Ebay images, you just have to "look through" the glue, or look at the edges of the lugs, where there is hardly any glue. The wood there is just too dark to be Maple.
If the bearing edge (of a wrapped shell) is not painted over, and/or not too messed up, you should be able to make out the outer ply wood type if you already know it's either Maple or Mahogany.
Hopefully this helps for any future endeavors :p