The photo sessions you do at the resorts are completely separate from the PhotoPass service in the parks. The private sessions at the resorts are done by PhotoPass photographers (read, not completely professional photographers), but they are priced serparately.
The resort sessions are just you and your family. You make a reservation for a specific time. They last about 20-30 minutes. They will take as many photos as you want during that time. And they will take you all over the resort for pictures. You can choose the areas and/or they will suggest some. You can pay extra for more time.
You used to be able to get a discount on the resort sessions if you had preordered the general PhotoPass CD, but they recently changed that. Now, if you book through Disney, you sometimes get a coupon mailed to you for 20% off the resort session. You have to bring in the paper coupon to get the discount.
The session starts at about $50 and goes to about $100. The $50 session includes just some prints and the session. The $100 includes a separate PhotoPass CD of all the resort session images and some prints. You can choose from different sizes of print packages. Again, all of these prints and the CD are different than the PhotoPass CD you can preorder that includes your park pics.
All of that being said, if you want free family photos at a resort, you can just go to any of the PhotoPass resorts (AKL, WL, Poly, Beach Club (I think), GF) in the evenings or sometimes the mornings and the PhotoPass photographers usually have a place set up with a nice backdrop and lighting to take family pictures. These sessions are free. No appointments can be made. First come, first served. When I stayed at AKL, there was never more than 1 family in front of us. 10 minute wait max. The photographer will take as many photos as you want with that backdrop and add all the photos to your general PhotoPass for free. Great deal if you preorder the general PhotoPass CD for $99.
