Both Nominal and PPP are out of whack if you are looking to learn about conditions on the ground. GDP measures the production of a certain country (and it's a very bad metric at that). Some countries are wealthy because its people make money from foreign sources. This is usually displayed by a high and chronic trade deficit.

That means you can have two countries with comparable GDP per-capita, where one of them have a more affluent population and able to pay higher prices.