The difficulty to compare network simulators is a major obstacle to the broader adoption of these tools. This problem particularly affects 802.11 simulators because the 802.11 protocol is complex and simulators contain several simplifications that are difficult to evaluate. In this paper, we present a generic visualization system able to interface with the 802.11 protocol implemented in NS-2 and Glomosim. Our tool allows to emphasize the common behaviours and divergences observed between the simulators and the IEEE 802.11 standard. Our contribution includes the definition of a new method to compare simulators and the publication of the most complete list to date of modeling differences relative to NS-2 and Glomosim lower layers.