What are the principal differences between presidential and parliamentary systems of government?
Not much lately. Presidential systems put (almost) all the power in the hands of one, the president. Parliamentary systems put the power in a parliament where (ideally) there’s a wider representation of the people, many representatives, many different positions. Most socialist democracies are a mixed system, with a president and a parliament (or congress). It’s supposed to balance the power putting the president in charge of the execution of policies and the congress in charge of the legislation. However, almost all executive branches take the legislative power through a congress cession or de facto. And almost all constitutions explicitly prohibit that. That makes the system a joke. A tyranny in the hands of only one and usually a loonie. Just take a look around you and you’ll see that representative democracies don’t exist anymore. Almost all have turned into tyrannical socialist systems.