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Orbital:  " ... usually represented by a picture that shows the boundary of the space surrounding the nucleus of an atom within which there is some finite probability (such as 90%) of finding the electron" or two paired electrons.
S.N.Ege, Organic Chemistry, Structure and Reactivity, Heath and Company, Lexington, Massechusetts, 19943.

Photos 1-3: Three different hybridized atomic orbitals (AO) of the C atom modelled by black beads and microbeads.
Right: Molecular orbitals (MO) formed by the overlap of sp3 hybrid AO with s-Orbitals of four H atoms.
A tetrahedral structure of the metahne molecule is formed.


Orbital hybridization: " According to this idea, overlap of hybrid atomic orbitals instead of the pure atomic orbitals of atoms forms molecular orbitals. Hybrid orbitals are mathematical combinations of atomic orbitals.....
Methane has four identical sigma bonds ..... the eight bonding electrons of methane are localized in four equivalent carbon - hydrogen bonds directed to the corners of a tetrahydron."  S. N. Ege,  Organic chemistry, D.C Heath and Company, Lexington, Ma 19943)