Jungle is a more complex genre of music than drum and bass (when it comes to talking about the beat, or drum rolls). Drum and Bass has more of a minimal beat, where as Jungle has more amens and more complex drum rolls. Jungle is mostly accompanied with reggae vocals (Ragga Jungle).
Compare any Ragga Jungle track to any Drum and Bass track that you know. You'll be able to hear the difference yourself.
melz is a wonderful creature originating from www.jungletrain.net chatroom. Can usually be spotted laughing hysterically, talking to herself out loud, or listening to the great DnB sets of SeaBass from The Pond (Friday nights on www.jungletrain.net).