Oh yeah, if you think of the fact that Ornn wrestling the earth literally shaped the mountains and he also built the MASSIVE howling abyss, Volibear's description of having "limbs as large as a man" does not exactly match up how absolutely massive Ornn is.
Gods in many universes come down as an avatar, or a very small portion of their true power (which is still unfathomable by mortal minds) to interact with mortals on their level or have a more realistic way of interacting with them. Based on Volibear's need to be "reborn" and the fact that his avatar had half his face missing, I'm guessing Ornn beat his ass. The oily description of the destroyed half of his face makes me thing Ornn literally melted it off and destroyed Volibear's true form, and we also know from Ornn's lore that he feels the need to come out into the world once again because Volibear is meddling in mortal affairs. I dunno about you, but Volibear seems like the type of god who would permanently be "meddling" if he had the chance, and papa Ornn sounds like he's gonna come out and slap down Volibear once again.
I'm also wondering how Anivia fits into all this. We can guess she's benevolent but honestly we don't really know much about her yet, I'd love to see how she and other gods in the Frejlord think of the sibling rivalry of Ornn and Volibear.