Whats the difference between a Red Dragon and a Green Dragon?

There are no differences, maybe color? But probably that's it. Dragons have a very high tolerance to heavy metal poisoning, have even come to incorporate such into their metabolism. The scales of the Dragon are a major site for heavy metal deposition and the colour of them is an indication of which heavy metals the particular Dragon is infused with. A Red dragon is probably contaminated with excess Iron or Mercury as the oxides of both are orange and crimson respectively. A Green Dragon would be infused with lots of copper as certain oxides of copper are a bright green, while others are a dark green. Red Dragons are sometimes more aggressive than Green Dragons.