How ca i better understand Socialism and capitalism?

Chavez uses nationalized oil revenue to cut poverty in half and that is bad for oil company profit and called Bush a A hole for not letting Chavez give us cheap oil right after Katrina. Castro kicked out all the big American companies in the 50s that were interfering with elections. Where I get confused is that China is no less capitalistic then the US only they are still communist. Socialism can be social programs like student loans and Welfare for those left out under fiat currency. Medicare, GI bill for troops.