What the difference between "Hell" & "Gehenna"?

As you mentioned, Gehenna was a garbage dump outside Jerusalem. Jesus used it as an example for the fate of the wicked. The bodies of executed criminals were dumped there to be destroyed by the constantly burning fire in the dump. Note: no one living was thrown in Gehenna and the bodies that were thrown there were completely destroyed by fire. This paints an entirely different picture then what mainstream Christianity claims will happen to the wicked. They have left the teachings of Jesus and Gehenna behind and adopted Dante's vision of hell and eternal torment.