Dragon bloodlines ->

1. Dragon beast - lowest of all dragon bloodlines. Dragon beast are dragons who does not have intelligence and are like animals.

2. Lesser dragons - dragons who have intelligence but can not transform in humanoid forms.

3. Greater dragons - dragons who have intelligence and can transform only after reaching adult stage

4. Pure blooded dragon - can transform from birth

and are treated like nobles among dragons

5. True blooded dragon - second highest rank in dragon bloodlines and are treated like royals among dragons

6. Celestial dragons - celestial dragons are the rarest and the strongest of all the dragons and are almost god like existence among dragons

[ Note: bloodlines affect the strength of dragons of same ranks, for example a lesser dragon of adult stage will be weaker than a greater dragon of same stage ]

There are also many dragon sub species like drake, wyvern, etc

Dragons have a very low fertility rate that is why they are very protective of their young ones