Yellowstone volcanism is associated with more magma-water interactions. 

Yellowstone's volcanism is more mafic because the mantle plume is below oceanic crust resulting in more mafic and lower viscosity magma. 

Yellowstone's volcanism is caused by a subduction zone on the east side of the North American plate. 

Yellowstone volcanism sits within continental crust resulting in more felsic-intermediate magma compositions and thus more explosive volcanic eruptions.