Obviously, this depends on region, year, and the wealth of the individual lord. Here, I'll talk about my area of expertise; northern Italy, in the year 1170.

In the year 1170, taking on the example of a fictional Knight (the lowest rung on the medieval feudal ladder); called, say for the sake of argument, Alberto of Giussano. Alberto would have the biggest house in the village of Giussano (maybe with a tower) in his village of no more than a dozen houses (all this is for the sake of argument, I don't know the actual population of Giussano in 1170. It's Friday night and I'm posting this from mobile on the subway home. I could probably find primary sources attesting the actual 1170 population of Giussano by Monday). In this case, the serfs tied to the surrounding lands might be bound by a number of agreements, having to work on their lord's land a few days a week, or having to be at his disposal for various tasks, including tasks around the house, he could assign at will on certain days (or a combination of both). Various household chores would be either performed or overseen by Alberto's wife, unmarried sisters, children, and help called up for stretches of time from the village. In his permanent employ, he might have a butter maker and a gamekeeper.

Now, historically speaking, Alberto's suzerain would have been the bishop of Monza. But let's say (always for the sake of argument, within historical plausibility) that he's squabbled with the Bishop of Monza, and shifted allegiance to Count Pagano Della Torre. Count Pagano (who really existed) was Count of Val Sassina, directly to the north, and held court in the fortified town of Primaluna, about a half-day's journey from Giussano. Pagano, having multiple vavasours and a large income, was a relatively powerful lord. In his household, he would have had several permanent servants, however, most menial jobs would have been performed by children, either his own or those of his relatives sent to stay with him. Indeed, sending children to work in a relative's household was commonplace in the middle ages (with older children being entrusted with more complex tasks, eventually being gradually involved in the management of family estates in their teens. And yes, in battle they might accompany older family members as squires, which was a fancy way of saying servant that's related to you). Servants were most likely employed in two basic services: preparing food, which would have been overseen by his wife (and unmarried sisters) and defending him. Servants employed in defense were called Sergeants. In battle, they would don armor and stand at the end of a line of about ten conscripts, pushing against the ends of the line so that the conscripts held fast, and presented a compact line of spears to the enemy (recall that battles were mostly mobs of people shoving each other in this point in time). However, most of their duties would be accompanying Pagano in Milan (where he spent most of his time), where he was a Capitano, or one of the people chosen to rule the city along with the Bishop, his nominal overlord. In his absence, there would have most likely been a Steward overseeing Primaluna in his stead. Most probably a brother of his (or his son, if he was old enough), but it might also be a particularly well trusted vassal of his (and most of the time, trusted = relative).

The Bishop of Milan in the year 1170 would have had the most complex household. Overlord to the Capitani families, recipient of a significant income, and resident in the Arcbishop's Palace in Milan (the decrepit building with walled-up windows near the present-day Royal Palace, not the baroque building the Bishop currently resides in) the Bishop of Milan would be able to pick the most able sons of the Capitani to defend him, he would have dozens of servants in his kitchen, he would not have to send his spouse out to round up the girls of the city to do his laundry, because he would have had laundresses working for him (and he wouldn't have been married, but that's not the point). Further, as the bishop had ecclesiastical duties to fulfill as well as political issues to deal with and keep track of (including, but not limited to, the Pope, the Holy Roman Emperor, jealous neighbors, jealous Capitani, and in general keeping the Capitani from killing each other) there would be administrators to deal with the apparatus of the bizarre communal/feudal state. In this case, the chief administrators managing the estates, income, and vassals of the bishop were the Cattaneo family, who held lordship of of Marliano and Massino (maybe you're wondering what would happen if a member of this family of administrators, or Vice-counts, if you will, were to be elected to become bishop. That's a story for another time).

In other parts of europe, say with a French knight, his lord, and the count of, I don't know, Picardy, the difference in households would be similar, but not completely analogous.

If you'd like to know more, I'd say check out The Medieval Household in Christian Europe, by Beattie, Maslakovic, and Jones (Brepols, 2003). It's a collection of essays on the medieval household. You can also look at Feudal Society by Bloch (Routlege,1989) (volume two specifically talks about the organization of social classes in Medieval Society).