2006 Envoy Denali AWD understanding

I have looked far and near and can not come to a clearer understanding of the listing of AWD for this Envoy I am looking at. I have seen 2wd and 4wd listings, but not an all wheel drive. This is not a 4x4 model for sure. Did GMC offer a AWD along with 2wd and 4wd ?? If this AWD option exists, anybody have any issues with AWD ???? Thx