::
That’s kind of loaded question. There are many differences but for the exam I could boil it down to two words for you; subsistence level. Classical theory contends that any growth in gdp per capita above that nations mean reverting level, or subsistence level, will cause a people to feel wealthier and hence be able to afford more babies. More babies, more people, bigger population which is a larger denominator in the gdp per capita ratio. Bringing us back to subsistence. This is not supported in empirical evidence though.