When firms in oligopoly; produce homogenous products it is called perfect oligopoly, whereas when firms produce differentiated products it is called imperfect oligopoly.
Detailed Answer:
Perfect Oligopoly: If the firm produces homogeneous product, then it is called perfect oligopoly.
eg. : Cement, Steel, producing industries, etc.
Imperfect Oligopoly: If the firm produces differentiated product, then it is called imperfect oligopoly.
eg. : Cars, soft drinks, etc.
