In general they share textures and nothing else. And even in textures there are minor differencies. They share hair pretty well, most hair have fit-poses to make it fit all the characters. Freak and Michael share face morphs (most of them at least) They can all use each other's poses, but some tweaking may be needed.

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You just can't put the words "Poserites" and "happy" in the same sentence - didn't you know that? LaurieA
  Using Poser since 2002. Currently at Version 11.1 - Win 10.