Answer : The serf enjoys the possession and use of an instrument of production, a piece of land, in exchange for which he hands over a part of his product or performs labour. 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 frees himself either by running away to the town and there becoming a handicraftsman or by giving his landlord money instead of labour and products, thereby becoming a free tenant; or by driving his feudal lord away and himself becoming a proprietor, in short, by entering in one way or another into the owning class and into competition. The proletarian frees himself by abolishing competition, private property and all class differences.

-The Principles of Communism

We cannot simply pretend the serf and the proletarian share the same nature of exploitation, rather, Capitalism's unfettered thirst for growth drives further exploitation and misery despite producing abundance, while feudalism did not share the same thirst for absolute growth overall, as technology largely didn't allow for it until inventions in production that gave rise to the Proletariat and Bourgeoisie.

The serfs had it worse, but owned more of their production.