Both demesne and enfeoffed manors require knight-service; demesne manor is no longer free money absent of a knight.

The difference is clarified in Book of the Warlord, p. 165:
"Demesne/Enfeoffed: Demesne is land (and
rights) over which the lord has direct control,
while enfeoffed holdings are portions of land
held by his vassals. Note that this depends on
the point of view. A king grants twenty manors
to a baron, who grants five of those manors to
his own vassal knights. The king considers all
twenty manors to be enfeoffed (held by his
vassal, the baron). The baron counts fifteen
manors as his demesne, and five manors
enfeoffed, while each of the five vassal knights
would consider his own manor to be a demesne