Führer is pretty much always associated with hitler, so we don't really use this word anymore.
Leiter is the person who leads something.
Generally Führer is someone who shows you the way (literally, like when you're walking somewhere), but a Leiter could also be someone who shows you how something is done.
There are some words who still use Führer though, like Fremdenführer or Führerschein. But on its own, we don't use Führer anymore