Hi... your post is confusing because you mentioned "click", but then used "hover" in the posted code. I assume that you meant to use "click" in the code.
The click command in _WD_ElementAction performs the default click functionality as defined in the Webdriver specs. The click command in _WD_ElementActionEx differs in the following ways --
Uses "actions" to perform the mouse click (pointer down followed by pointer up)
Allows control of which button is clicked (left, middle, right)
HTH, Dan