Oligopoly

What does it mean that product differentiation in Oligopoly is homogeneous/ standardized? I might expect homogeneous or differentiated, because the products do not have to be the same, but standardized? Is it also supposed to mean there is no difference between oligopoly and perfect competition (as curriculum says perfect competition differentiation is aslo h/s)… And monopolistic competition is then the only one with differentiated products?

Thanks for explanation

Typical examples of oligopolies are:

Oil (standardized)

Aluminium and Steel (also standardized)

But I would not think that this is the case 100%, I think there are also plenty of examples where you have some differentiation:

Pharmaceuticals comes to mind (Commercials try to make you believe that the generic brand just isn’t as good)