about 5 years ago - UbiMorning - Direct link
From our DDoS response[rainbow6.ubisoft.com] post:

DDoS – An attack on the server, or network, from multiple PCs/devices that overloads the network. This results in all players being disconnected and the match ending.
DoS – An attack on the server, or network, from a single PC/device that overloads the connection. This sometimes results in all players being disconnected.