The opposite of socialism is not capitalism (that is a non sensical statement) - the opposite of socialism is something like fascism
China has a capitalist economic system but it is State run and centralised. THe US model of capitalism is Corporately run which is also centralised and protectionist
As far as the political system in the USA is concerned, it can be best described as a Corpocracy, an Oligarchical Corpocratic Welfare state catering for the Plutocrats.
The USA is certainly NOT democratic and its internal freedoms are provisionary and illusionary to say the least