From what I have read about these things is that Real GDP isn't actually the same as GDP PPP. The main reason of the former is to compare the production of goods and services while excluding inflation.
If nominal GDP uses the current prices on year-to-year basis, the Real GDP uses a so called basic year and the current prices are compared with this year, excluding inflation.
The main reason of GDP PPP is to compare the values of different currencies, and a special coefficient is used to do that.
Yes, the main flaw of nominal GDP is that it is based on the current prices and virtually doesn't mirror the amount of goods and services produced. For example, if France produces a car with the price of 5000 dollars and Greece produces an identical car that is priced on 2500 dollars, the France's nominal GDP will be twice of Greece's one, though they produced the equal amount.
But like it or not, the Frances economy will produce twice more money than Greece's.