d-orbital classification:

• Axial orbitals (lobes along axes): \(d_{z^2}\) and \(d_{x^2-y^2}\)
• Non-axial orbitals (lobes between axes): \(d_{xy}\), \(d_{xz}\), \(d_{yz}\)

The \(d_{z^2}\) orbital has lobes along the z-axis with a torus in the xy-plane. The \(d_{x^2-y^2}\) orbital has lobes along both x and y axes. These two are directly involved in ligand interactions in octahedral complexes (eg set).