A payment can be in one of the following states:
Waiting: a payment is in the waiting state when the payment order has already been created, but a transaction to fulfil it still has to be seen on the Bitcoin network
Received: a payment is considered as received when it appeared on the network, but it still has to be confirmed. Before considering the payment as finalised, it is advisable to wait until it gets in the confirmed state, especially for high value transactions, as before the network confirmation a risk of fraud still exists.
Confirmed: a payment is considered as confirmed once it has been successfully included in the Bitcoin blockchain and cannot be cancelled anymore.