I currently switched to iTerm2 + VIM for my dev environment. I noticed that the last version of iTerm2 supports tmux and there were people using tmux to split the window into several sessions. I also noticed that iTerm2 has options out of the box to split the window into several sessions. You can split as many sessions as you want vertically and horizontally by just using CMD+D for example. So to me it seems that you can accomplish the same functionality with those options. I could be totally wrong.
My questions is: Is there a difference/benefit by using tmux over the splitting options on iTerm2?