WPA vs WPA2
WPA uses the Temporal Key Integrity Protocol (TKIP) to dynamically vary the encryption key shared between the access point and connected clients. The continually changing key provides more secure authentication than the earlier WEP wireless encryption standard. WPA2 further improves Wi-Fi authentication with CCMP, the "Cipher Block Chaining Message Authentication Code Protocol," which requires a 128-bit key.
WPA uses the same RC4 encryption method as WEP, which is considered weak encryption by modern standards. WPA2 requires AES (Advanced Encryption Standard), which is significantly stronger and harder to break. AES encryption supports 128, 192, and 256-bit keys.
NOTE: Most Wi-Fi networks use WPA2 by default. If you are offered a choice between WEP, WPA, and WPA2, it is best to choose WPA2 since it is the most secure.