How does the institution of knighthood reflect the social system of feudalism?

A way to actually understand the social system of feudalism is by stablishing the difference between this and an empire in terms of social position.

Explanation:

the feudalism comes after the fall of empires, such as the roman, experienced and right after this, there was a constant fight for territories. In the meantime, a hierarchy was build and knights played a role as they were at the service of the tribe's king or the lord, who was rewarded by the king as a way to be thankful for the support. Knights, on the other hand, worked for the lord, but had the chance to get a better position, by means of military, serving the lord and ultimately, the king of the land (s).