I would say that when its longer it has less volume but more curls (and more friz) ... my hair will only curl a certain amount within a certain distance. So longer locks means my hair has more room to curl around and around and around. but the longer it is the the more the hair around my roots looks flat. I get a lot of compliments on my hair when it's longer but my issue is that the straight strands (right behind my ear and at the nape) grow longer faster than the curly strands (for obvious reasons) and they end up looking stringy and gross.
I also can't seem to pull off a pony tail when my hair is long. it just looks limp and sad. But when it's shorter like it is now its this curly poofy fun thing on the back of my head.
I think you are right Corrina, last night I used Deva no friz volumizing foam with just a couple spritz of the spray gel. I'm starting to learn my hair like light products and I have to be VERY careful not to use too much.