What was one difference between the Estates General and the National Assembly?
A. The Estates General was formed by the common people, while the
National Assembly was formed by Louis XVI.
B. The Estates General had existed for centuries, while the National
Assembly was formed in 1789.
C. The Estates General demanded a new constitution, while the
National Assembly supported Louis XVI.
D. The Estates General had legislative power, while the National
Assembly rejected a role in government.

B. The estates general has existed for centuries, while the national assembly was formed in 1789

Explanation:

The states General was first established in  1302. It was a form of legislative assembly where the government gathered a group of people from different classes in order to talk about policies.

So, some form of discussion between the ruling class and the common class has exist in France for centuries before the French revolution.

The national assembly was first held after the French Revolution. The purpose was to create a  new form of government to operate the country after they got rid of the nobles. They felt that even during the estates General, the ruling class only include the common class as toke without paying much attention to their issues.