In online covens here, the positions are (high) priestess, (high) priest, council, or member. Each of these positions can have different requirements depending on the coven, and each of them does have different permissions.
A member can post in a coven and can delete their posts.
A council can post in a coven, can delete their posts and the posts of others, and can add articles and spells to the coven spellbook.
A (high) priestess or priest can post in a coven, can delete their posts and the posts of others, can add articles and spells to the coven spellbook, can edit articles and spells in the coven spellbook, can accept or reject members into the coven, can promote, demote, or remove members, and can change the front page information and coven images (among a few other things).
That's the basic differences between the positions. Depending on the coven the (hig) priestess or (high) priest may be the main leader or the leadership may be shared equally. The two may work together as a unit or work as separate parts as a whole. They can require certain things of their members or their council and if the requirements are not met they can remove their members or demote their council. They essentially head the coven and decide where/how it goes. A few covens work as a democracy, with the members voting on what happens within the coven per the request of the leadership and there are other democratic covens that are entirely run by voting and have the two most responsible, knowledgeable, and active people.
A (high) priestess need not be female, nor does a (high) priest need to be male.