There is incomplete competition when the competitive situation is limited by restrictions of competition, especially by the market power of companies. In the event of incomplete competition, companies have the power to set prices. These are then higher than with full competition and thus reduce sales of the corresponding goods.
In contrast, perfect competition is more intense under liberalized market conditions. If competition is liberalized so far when competition is incomplete, then new providers enter the market and there are new innovative services. As a result of the intensified competition, prices are falling and demand is increasing.
See also "Full competition"