the Crest horns on the dragon are different for different genders, unless it is of 'royal' blood. Regardless of gender the 'royal' crest is always the same.

Tails always have barbs, they're used to smash the egg open when they hatch and as self defense. All dragons have a breath weapon, be it Ice, Fire or Poison. Dragons come in a wide range of colours, including shades of black to white.