There are quite a few different axolotl colour variants around, here I shall list some of the most common ones -
Wild types tend to vary from shade to shade, most dark brown with speckles of black and yellow - although some tend to even look tan.
Melanoid axolotls lack iridophores (the shiny patches on axolotls bodies and around their eyes). They have dark pigment cells (called melanophores), making them black.
Melanoids can be quite similar in appearance to Wild Types, but the best way to tell the difference between to two is to look at their eyes - wild types (and all other axolotl colours besides melanoids) will have a shiny ring around their pupil. While melanoids do not.
Albino axolotls lack melanophore pigments, showing the white colour of their skin. They have red/pink eyes due to the underling blood vessels showing through.
Golden albino have a golden colour, with red/pink eyes.
CopperCoppers are commonly found in Australia, although are hard to come by in most other countries.
Appearing like wild-types, coppers vary from shade to shade - most a caramel colour, although are also darker.
Unlike wildtypes, coppers are albinos. If you look closely at their eyes (a small torch may help), they will be red, even if they look dark. Like albinos, coppers lay white eggs.
Leucistic axolotls are very different from albinos, even though they are both white. Leucistics have reduced pigmentation in their body, resulting with their white colour. Sometimes can have speckles of black on them - this is also known as "piebald".
Leucistics always have black eyes, so to differentiate leucistics with albinos - look at their eyes (albinos have red/pink eyes).
While this lovely Leucistic of mine has red eyes, there is a black rim AROUND the red - indicating her Leucism.