Moses the bird is "spiritual" in the faux religion kind of way. While technically Moses supports "religion" by talking about Sugarcandy Mountain, his character is clearly hyperbolic and, as much else in Animal Farm, tongue-in-cheek. Moses is lazy, distracting, and ultimately unhelpful; Orwell clearly did not intend this character to represent any sort of real guidance.
Benjamin, on the other hand, repeatedly says true (if cryptic) things, mostly along the lines of "everything is awful." The only animal who doesn’t get caught up in an ideological frenzy, Benjamin quietly does his work while steadfastly maintaining his pessimist stance. The "guidance" he offers is therefore indirect; he is the only reality check, pillar of common sense guy that the animals have.