Looks like an axe to me. The cutting edge of the axe is embedded into the surface. And the handle attaches near the back of the head like an axe. Most hammers I've seen the handle attaches in the middle.
Splitting mauls have a wider angle to help separate wood pieces and a beefier back to use with/as a sledgehammer or splitting wedge. What's rendered is definitely more like an axe than a splitting maul.