It is a variant of the LAV--has some upgrades, but is not that different.
This site has some info on it:
http://www.paratrooper.net/aotw/commo/topic.asp?TOPIC_ID=3903&whichpage
I am not at home or I would have HTML'd that link for you
Stryker is not a Marine LAV-25. Here are the Advantages of the LAV-25 over the Stryker ITC (Infantry Troop Carrier):
1) LAV-25 is amphibious, Stryker is not.
2) LAV-25 is more nimble and cross country maneuverable due to 10,000+ lbs less weight. LAV-25 is around 14 tons and the Stryker is around 19 tons.
3) LAV-25 can be sling loaded by CH-53, Stryker cannot.
4) LAV-25 has 25mm bushmaster and turret. Stryker has remote mounted .50 cal OR Mk19.
5) LAV-25 is truely C-130 transportable, Most of the 10 Stryker varients are not.
6) LAV-25 costs 1/3 the price of a Stryker.