Well its their distinct appearances that grinds my gears (mostly)Sage Mode can be learned in two places, Mount Myōboku of the toads and Ryūchi Cave of the snakes. Learning Sage Mode at Mount Myōboku or Ryūchi Cave grants the user with a toad and snake style of Sage Mode respectively, which carries over the same advantages and disadvantages, only differing in application.
the bold part explains it, different application of nature energy gives you a different mode. its quite simple. your over thinking it