A better way to look at it would be top coil and bottom coil, with the wicks being at the coil. The top coil clearomizers generally give a warmer vape because the coil is nearer your mouth. The wicks hang down into the liquid, due to gravity working against the wicking it is necessary to tilt the
device regularly to keep the wicks saturated near the coil and prevent dry hits. The bottom coil
devices, of course then would have a cooler vape and are immersed in liquid so don't require the tilting. The top coil
devices were the first on the market and it's what I use, requires a little bit of technique to use, but work well. I like the warmish vapor and don't mind the tilting, it becomes second nature after a while. I've never used a bottom coil, so I won't go into them.