1. The Atmos has a smaller lighter top compartment with inside zip storage for easy access to small items (wallet, keys, cash.)
2. Storgage compartments on both sides of the hip belt for snacks and small items like sunscreen, repellant, pocket knife, lighter etc.
3. Two large outside storage pockets for easy access to rain gear and a pack cover.
4. Over two pounds lighter is a lot of weight savings just changing one item. That's huge.
Color: Graphite Gray - $199 at REI in Hillsboro, Oregon
I loaded all my gear in tonight and still had plenty of room for 7 to 10 days of food stuffs even with the reduction from 60 liters of storage down to 50 liters with the Atmos. Keeping in mind I want to be as comfortable as possible and balance out the need to keep things light for my back and legs. It's worth repeating that you should spare no expense on the best equipment and you'll never regret it. If you find out something doesn't work the way you anticipated then change it or suffer the consequences. Now it's time for gear trip #2 to make sure everything works as it should!