There are many existing resources that discuss the differences between WPA and WPA2. The following two links provide a good overview of the differences:
While CDRouter can simulate both WPA and WPA2 clients, it does not currently support mixed WPA/WPA2 schemes. This is due to differences in the RSN Information Element (RSN IE) and EAPOL-Key messages. As a result, CDRouter requires that the device under test be configured for either mode alone when testing WPA or WPA2 functionality.