Ok for those that don't know

first World - A capitalist country

second world - a communist country

third world - a developing country

I here it quite often, e.g. south africa isn't a first world country yet 

I find that most people don't even know what the second world is as it has all but disapeared. But is it cool to classify  south africa and zimbarbwe as the same? What is the differance between south africa and america that makes america first world and south africa third world? We drink coke in both we enjoy many of the same luxeries. The only noticable differance I can find is the unemployment rate. But is that what determines it? If so will america be a third world country if the economic depression hits to hard and lots of people lose there jobs? third world is discribed as developing so I don't think that is it anyway, but the truth is no country ever stops developing, new things are being built in America. Is it the rate of development? or a combonation of all of the above? But I would submit one other thing, location. People think of africa as the third world and so I think even if south africa  gets down to 20% unemployment we will still be seen as a third world country. I don't know if others agree with that but I think It is the case.  But really all im asking is why is america 1st world and south africa 3rd world? How would you make the judgement of when south africa moves up to first world?