Witches are all humans with the ability to use magic, cast spells, and more in that line.
Witch is used for women, and warlock is used for men within the community. Other supernaturals all them all witches generally.
Sorcerer/Sorceress are witches that made deals with beings of great power. (Demons, Gods, and other)
Druids are witches with massive expertise in nature magics.
Covens, family lines, etc. As unique and varied as humans can be.
They all answer to Johann and Mathilda on the Tribunal, but they have pockets of smaller governments.
Ah damn. This will take a long time to fill out.