I've seen walkaround for the 4x4 VAB vehicle, but none for the 6x6. Are there any differences besides the extra set of wheels?

There are many variants of the 4x4 with different looking topsides so I suppose that the question concerns the differences in the basic chassis?
The 6x6 is an export version, most of the exported vehicles were 6x6. The French Army only use the 4x4.
This wikipedia article has a list of users:
https://en.wikipedia.org/wiki/V%C3%A9hicule_de_l%27Avant_Blind%C3%A9
Since the 6x6 was only for export I think that walkarounds may be hard to find considering the countries that use it. I don't think Italy had any 6x6 either ...
/ Robin

I was thinking along the lines of vehicles on display for customers.

The upgraded versions of the VAB 4x4 and possibly also 6x6 went into production in 1990 so most of the marketing and photo sessions at defence exhibitions would have taken place before that and images from that time are less frequent on the internet ...

You'll find a few pics of 6x6 VAB's in various configurations here :

http://www.maquetland.com/phototheque/19-maquetvciapcvbmr/7-france

Apparently, Italy has bought the 120 mm mortar carrier 6x6 version (VAB 2R2M) - but I've yet to see a picture to confirm this - and the NBC version below :



http://www.ferreamole.it/images/vab/vab_01.htm

The VAB family of vehicles on Chars-français.net :

https://www.chars-francais.net/2015/index.php/154-archives/de-1945-1990/vab

H.P.