The clergy and the nobility (also called the First Estate and the Second Estate, respectively) were privileged both in terms of economics and political power.
Economically, we should not think that all of the first two estates and none of the third were wealthy. Many in the third estate were wealthy because they were merchants or professionals. However, the great majority of the tax burden fell only on the Third Estate because the first two enjoyed many exemptions from taxes.
Politically, the first two estates had much more power than they should have had based on their numbers. In the Estates General, each estate was represented equally. This was true even though the Third Estate had something like 98% of the population. Thus, the first two estates had political power far beyond what they should have had.