WPA Personal vs. Enterprise ?
WPA-Personal (a.k.a. WPA-PSK) is a common method to secure wireless networks. In the Personal mode, a pre-shared key or passphrase is used for authentication. This pre-shared key is then dynamically sent between the AP and clients.
WPA-Enterprise (a.k.a. WPA-802.1x, RADIUS) includes all of the features of WPA-Personal (WPA-PSK) plus support for 802.1x RADIUS authentication and is appropriate in those cases where a RADIUS server is deployed. WPA-Enterprise should only be used when a RADIUS server is connected for client authentication.
With WPA/WPA2 Personal you need to add all users to all APs (access points), in Enterprise mode you use a central database on a 802.1x RADIUS server.
See also: TKIP or AES encryption ?