As dragons accumulate energies as they grow up, taking on different powers. Below are the classifications based on color; these are not cultural or national designations. A dragon can be of any draconic nation and take on any of these colors, depending on the energies it takes on. However, some draconic nations have tendencies toward certain energies (esp. aquatic ones, for instance). Most dragons lock into a color by maturity, but it is possible change later if a sufficient amount of energy is accumulated somehow.
Like all creatures, dragons' powers, abilities, etc. change over time, but theirs is on a greater scale. As they live for up to 100,000 years, they have a different arc than most:
Egg
Hatchling: worm stage, usually for about three years
Adolescent dragon: begins taking on a hue, usually from three to 100
Mature dragon: locked into hue, usually from about 100 to 1,000
Senior dragon: greater powers, usually from about 1,000 to 10,000
Greater dragon: much greater powers, usually from about 10,000 to 25,000
Elder dragon: some powers decline, some increase, usually from about 25,000 to 50,000
Ancient dragon: most powers decline, some increase, usually from 50,000 to 99,000
Epochal dragon: the rare dragon who reaches around 99,000 years of age regains all lost powers and for their last 1,000 years, they are extremely powerful