Kinky..
The prop maps are what you use as a guide to lay your textures so they align with the prop once the textured prop map is applied.
The overlay is like a "shadow" version of the prop map. Once you have your map done (all textures applied), place the overlay on top. It will apply the shadowing for you so looks much better.
Not all prop maps have an overlay available.
I hope this helps.. Hugs..BB
Damn you, Addamant, for turning me into a forum whore! *shakes fist*
_Monk_: What does BB stand for?
_Monk_: Ball busting? hehehehe