What is the difference between a vassal and a knight?

The terms "vassal" and "knight" both refer to roles within the feudal system in medieval Europe, but they describe different positions within that system.

A vassal was a person who had entered into a mutual obligation to a lord or monarch. This typically involved a formal ceremony where the vassal pledged fealty (loyalty) to the lord, and in return, the lord granted the vassal a fief—a piece of land to control and use for generating income. The vassal's responsibilities included military service to the lord, participation in the lord's court and advice, and potentially financial payments or services. A vassal could be a nobleman, with his own vassals underneath him, or someone of a lower status, depending on the size of the land grant and the nature of the services owed.

A knight, on the other hand, was originally a trained heavy cavalryman of noble birth. Over time, the term came to be associated more broadly with members of the warrior class who followed a code of conduct known as chivalry. Knights would often serve a lord as part of their military service, but they could also be freelance or attached to the church as well as to various lords. Being a knight was more about a social position and a profession, rather than a political relationship or land ownership, though many knights also became vassals if they were granted land by a lord as a reward for service.

In summary, a vassal is defined by their relationship to a lord through the fief and vassalage system, whereas a knight is defined by their role as a mounted warrior and their adherence to the chivalric code.