I have all my life been an open faced spin casting guy. I have seen many threads saying something on the line, "Bait casting rod" or "Spin casting rod"

What makes a rod spin cast vs bait cast. I know the difference in reels of course but how about the rod. Different mounting hardware?? Different grip??

Sound to me like a stupid question but I thought you could put any reel on any rod as long as you were confortable with it.