A Well or Evil Well are the same = Basically known as an Evil Well
A Map can ONLY spawn an Evil Well if it STATES +X Evil Wells

Evil Wells can ONLY been found in catacombs [randomly], whereas a Map with +X Evil Wells are guaranteed to be found when exploring that Map.

Invisible Well being superior is bullshit, the only reason why the "Evil Well" is invisible is because the packet transfer of the graphics for that 'Well' in the catacomb or map were lost when downloading.