I know the Mages Guilds in Cyrodiil split up between those two factions in the 4th Era, but I would like to know specifically which Mages Guild's are in what one of those factions.
I couldn't find the answer looking myself.

I really only need to know which faction the Leyawiin Mages Guild belongs too.

Thank you

It's more about people and not locations, at least that's what I guess. Maybe the old Leyawiin guild hall (in case it still stands) is "currently" being used for something entirely different.

As far as I know, we know close to nothing about the Synod and the CoW. That also includes if the Leyawiin guild hall now belongs to the Synod, the CoW or something else.

The College of Whispers seem to enjoy "hidden" magics. Stuff that became frowned upon in the aftermath of the Oblivion Crisis. Summoning Daedra and necromancy seem to be the big ones.

So personally, I like to believe that the College is made up of former Mage's Guild members associated with the Worm Cult, who, after Mannimarco's mortal avatar (or whatever the hell he was) was struck down decided to try a more mainstream route for gaining legitimacy.

Hmm, the way its said though seems like the two factions were made by a division of the former Mages guilds rather than people, as J'zargo mentions hes been to them both as if they were a place to go.

Something in the back of my mind is telling me the Arcane university only is the College of Whispers and the rest of the Mages guilds in the other towns would be the Synod.

anyway, If I can't find a definite answer, I'll need to make the most logical sense of it and decide myself