  We report the temperature evolution of the detailed electronic band structure
in FeSe single-crystals measured by angle-resolved photoemission spectroscopy
(ARPES), including the degeneracy removal of the $d_{xz}$ and $d_{yz}$ orbitals
at the $\Gamma$/Z and M points, and the orbital-selective hybridization between
the $d_{xy}$ and $d_{xz/yz}$ orbitals. The temperature dependences of the
splittings at the $\Gamma$/Z and M points are different, indicating that they
are controlled by different order parameters. The splitting at the M point is
closely related to the structural transition and is attributed to orbital
ordering defined on Fe-Fe bonds with a $d$-wave form in the reciprocal space
that breaks the rotational symmetry. In contrast, the band splitting at the
$\Gamma$ points remains at temperature far above the structural transition.
Although the origin of this latter splitting remains unclear, our experimental
results exclude the previously proposed ferro-orbital ordering scenario.
