The greatest difference is in the bass drums. The one over on the left is an all around drum. It plays loud enough, it plays quiet enough, and always with sufficient punch and a lot of tone. It opens up no matter how it's struck, and for some reason I want to describe it as being more musical than the other two.
The one in the middle plays quiet and, compared to the teardrop, has a muted and velvety sound. Very controlled and focused tone, with a range from
ppp to
mp. Trying for more than moderate volume isn't particularly rewarding, but depending on your foot, it will produce a moderately loud attack with diminished tone. It's greatest strength is that it provides a wide range of subtle gradations within a fairly narrow range of volume. The word is control.
The thing on the right bears a family resemblance to the 18 in its velvety tone, but that and its looks are about where the similarity ends. Sure, you can play the 20 quietly, but it doesn't really open its voice at anything less than a medium strong rock stroke. From there, it doesn't quit, and it is capable of producing the kind of volume that can stun a house into silence with its force and resonance.
A guy would be wearing out his foot and the equipment on the teardrop trying to keep up with the 20" Designer. Once the Designer is on the pipe, you just sit back in the chair and let it rip. The teardrop has a more useful dynamic range, in my opinion, for most things. But if I ever get the call for Wagner' Götterdämmerung, when Valhalla and the gods are consumed in flame, I've got the drum.