Is it a real pension where my money is invested and returned to me in 20 years or is it like pensions in Europe, where you pay taxes that pay out current pensio

Is it a real pension where my money is invested and returned to me in 20 years or is it like pensions in Europe, where you pay taxes that pay out current pensions and then you hope the government will give you X money in 20 years (which will inevitably become 30 years and X/2 by the time of your pension age)?