Feudalism organised medieval European political and military society around a chain of personal obligations: a lord granted land, a fief, to a vassal, and in return the vassal owed the lord military service and personal loyalty, an arrangement that repeated in layers up and down a genuine hierarchy from king to great lords to lesser knights. Manorialism organised the actual economic life happening on that granted land, with peasants working the fields in exchange for the lord's protection and the right to work a portion of the land for their own subsistence. Feudalism and manorialism operated together, one structuring political and military obligation, the other structuring the actual day-to-day agricultural economy underneath it.
Feudalism bound the noble and knightly classes together through mutual, personal obligation
A feudal relationship was a genuinely personal, reciprocal bond, not simply a property transaction: a vassal swore explicit loyalty to their lord and owed real military service when called on, while the lord owed the vassal protection and the continued use of the granted land in return. This layered structure, king to great lords, great lords to lesser knights, meant political and military obligation ran through a genuine chain of personal relationships rather than through any centralised bureaucratic state apparatus, which is exactly why medieval European political power was so genuinely decentralised and fragmented compared to a more centrally administered empire.
Manorialism organised the peasants actually working the land underneath that structure
Manorialism governed the relationship between a lord and the peasants, many of them serfs bound to the land itself, who actually worked a manor's fields, owing the lord labour and a portion of their harvest in exchange for protection and the right to farm a portion of the land for their own family's subsistence. This economic arrangement operated at essentially every level of the feudal hierarchy simultaneously, meaning the same knight who owed military service upward to a greater lord was themselves the lord receiving labour and produce from the peasants working their own manor, feudalism and manorialism interlocking at every rung of the same overall social structure.
What we're still unsure about
That feudalism structured political and military obligation through personal lord-vassal relationships, while manorialism structured the underlying agricultural economy, are well established, extensively documented features of medieval European society. What's more genuinely a matter of ongoing historical debate is exactly how uniformly and systematically "feudalism" as a single coherent system actually operated across medieval Europe, since historians have increasingly questioned whether the tidy, textbook version of feudalism was ever quite as consistent and formalised in practice as later historical writing sometimes presented it, and medieval historians continue to debate how much regional variation and informal practice sat underneath the general feudal and manorial pattern.
This sits inside Feudalism & Manorial Society in Europe, one of eight topics in Medieval History, one of seven domains in History, one of seventeen subjects the app can quiz you on.