By that I mean if they all fight the same : use a +40 damage staff of fireballs ?

Ive just defeated Vokun last night on my Nord Dragonborn warrior and I remembered fighting Krosis on my assasin and he used the same attack.

Are they all the same? Ive only killed Vokun and Krosis.

No Hevnoraak for example has a staff of wall of storms

I'm pretty sure Otar the Mad uses somekind of lightning staff. Haven't seen him for a while.
And Morokei has some other tricks up his sleeve.