Drawing on the works of Ostrom, the paper seeks to establish the bases on which the "traditional" commons (TC) and the "knowledge" commons (KC) can be compared and differentiated. Three criteria are proposed: the nature of the goods or systems of resources, the property regimes and the modes of governance. On this basis, the two large families of commons (traditional/informational) are distinguished as follows: - Nature of the goods. While TC are composed of tangible and rival goods, KC are composed of non-rival goods; - Property regimes. The essential difference (between TC and KC) lies in the fact that in TC, the basic right given the to "authorized users" is designed to guarantee the long-term reproduction of the resource, whereas in KC, beside the right to withdraw resources from the CPR, another and complementary right is defined ; namely a right of addition. In KC, the authorized users are allowed and encouraged to contribute new information or knowledge to the pool. It is often for this very reason that the pool has been created. - Mode of governance. Whereas TC are oriented towards the reproduction of the shared resources, KC are oriented towards their continual enrichment (databases, open source software, wikis, etc.). Finally, if TC are above all organizations aiming at the orderly exploitation and long-term conservation of resources, many KCs and the most prominent one (FLOSS, wikis, ..) are conceived primarily as tools for the growth and enrichment of the pool of resources through cooperative procedures aiming at promoting modes of production of innovation based on information sharing.