To elucidate the similarities and differences between the physics displayed by orbital and spin degrees of freedom, we analyze an orbital‐Hubbard model with two orbital flavors, corresponding to pseudospin 1/2, and contrast its behavior with that of the familiar (spin‐1/2) Hubbard model. The orbital‐Hubbard model describes a partly filled spin‐polarizedegband on a cubic lattice, as occurs in ferromagnetic manganites. We demonstrate that the absence of SU(2) invariance in orbital space has important implications — superexchange contributes in all orbital ordered states, the Nagaoka theorem does not apply, and the kinetic energy is enhanced as compared with the spin case. As a result orbital‐ordered states are destabilized by doping, and instead a strongly correlatedorbital liquidwith disordered orbitals is realized. © 2003 American Institute of Physics