[Off topic] Difference between wpa: tkip & aes

[Jar]

Hello

With Liksys wrt54g AP I can select WPA-PSK and then I have two alternatives: TKIP
and AES. When I capture some packets with wireless sniffer and then comparing these
two methods (tkip/aes), I can't see no dirrerence. In both cases the APs beacon
probes looks like the same and also the data packets seems to be only TKIP/WEP
protected in both cases. I can't see AES or CCMP anywhere even if the WPA-PSK/AES is
selected, should I? What is the dirrefence between TKIP/AES?

It is also possible to select WPA2-PSK and then again two alternatives: TKIP and
AES. Can someone explain the magic behind these modes?

I want to use WPA-PSK with AES. What should I look for in the sniffed packets to
ensure that the encryption uses AES and not TKIP/WEP?

-- 
Best Regards, Jar