A. Market based, in which a certain reward is provided for performing a certain amount of work. Workers are generally free to come and leave, and respond accordingly to variations in wages.
B. Command based, into which workers are essentially corralled by threats of force (explicit or implicit), and often provided with nourishment so they can keep laboring until their obligation is fulfilled.
It's possible to talk of "payment" under scenario B [1], but it cheapens the term and it definitely doesn't indicate market-based relations. Transfers of food and drink (which make for poor currency, especially in places that are already minting coins [2]) are on the contrary a good indication of the corvée system at work.
[1] See e.g. this Wikipedia entry: "Corvée [...] was unpaid labour imposed [...] by the state [...] The corvée was the earliest and most widespread form of taxation [... The] Medieval agricultural corvée was not entirely unpaid: by custom the workers could expect small payments, often in the form of food and drink consumed on the spot." http://en.wikipedia.org/wiki/Corvee