Price Skimming: You can charge a high price because you have a substantial competitive advantage, or because there is a shortage in the market. However, the high price is not sustainable, it actually attracts new competitors into the market, and the price inevitably falls due to increased supply.
Premium Pricing: You use a high price because there is uniqueness about the product or service you offer. This approach is used where a substantial competitive advantage exists. Such high prices are charged for example for specialty coffees