Here's what Fessel & Balzer says on "Native Philippine Orchids":-
Phalaenopsis x intermedia - a natural hybrid between P. aphrodite and P. equestris. Size and form is intermediate between the two species.
Phalaenopsis amabilis vs Phalaenopsis aphrodite - The former is distinguishable by its narrower apical art of the lip and the green underside of the leaves.
Well, there's one version of the differences... does anyone grow these two to confirm?