Melo death is Gothenburg. Melodic death is just that, melodic death metal. The former is a misnomer. When I was younger I would make the argument that viking metal and folk metal are two different things, too. The former being shit like Moonsorrow and Tyr, maybe using keyboards, the latter using actual folk instruments. I'm not sure if I would bother arguing that anymore, but melo-death and melodic death are definitly different.