I found the thread I mentioned from a few years ago, which prompted me to take the photo. Link is to that post, in that post I listed the purpose for each bag:
Use stuff sacks or not?
Originally Posted by
TiHabanero
60L backpack? That is a lot of stuff, but I like the way you have organized it. Very similar to what i have done.
70 liter backpack. Two weeks, but I did resupply food, camera batteries, GPS and headlamp batteries (AA), and butane half way through. Solo, so I was carrying all the cooking gear, tent etc., nobody else to help with the community gear.
Last summer I had a 9 day backpacking trip, used an 85 liter pack for that, the 70 was too small with that much food and stove fuel.