Feudalism is Feudalism. Capitalism revolves around competition, Capital accumumalation, and industrialization, whereas feudalism is a monopolic assurance of rent in exchange for protection.

To quote Engels, in Principles of Communism:

"The serf possesses and uses an instrument of production, a piece of land, in exchange for which he gives up a part of his product or part of the services of his labor.

The proletarian works with the instruments of production of another, for the account of this other, in exchange for a part of the product.

The serf gives up, the proletarian receives. The serf has an assured existence, the proletarian has not. The serf is outside competition, the proletarian is in it.

The serf liberates himself in one of three ways: either he runs away to the city and there becomes a handicraftsman; or, instead of products and services, he gives money to his lord and thereby becomes a free tenant; or he overthrows his feudal lord and himself becomes a property owner. In short, by one route or another, he gets into the owning class and enters into competition. The proletarian liberates himself by abolishing competition, private property, and all class differences."

It is in this manner that the Bourgeoisie were actually once a revolutionary class against the Nobility, along with Proletarians. Because advancements in productivity via industrialization lead to advancements in Mode of Production, Capitalism overtook Feudalism and a new ruling class, the Bourgeoisie, cemented their place.