What? Please re-read my #57. According to the notes from the CIA World Factbook on "GDP methodology": "In developing countries with weak currencies the exchange rate estimate of GDP in dollars is typically one-fourth to one-half the PPP estimate."
In other words, if you convert Egypt's GDP into dollars at the official exchange rate, it might turn out to be as low as $70 billion instead of $268 billion. That's all.
The data derived from the PPP method provide the best available starting point for comparisons of economic strength and well-being between countries.
If you want to compare two countries . .... this is how to do it.