Where the
coils are... relative to the
juice level, the user's mouth and how they are filled.
BC clearos do not require the occasional "tip" onto their sides to ensure there's
juice on the wick. Although I've not used clearos in a long time, even long wicked TC clearos, like the iClear 30... unless I've re-wicked them with cotton or my own silica, I personally don't trust their capillary action qualities below half full - and will tip them to the side.
It sounds like some sort of unreasonable requirement...
"Tipping? That is just such exhausting work!" - but in reality, more often than not, the tipping action is as automatic as blinking.
All else equal, clearos and glassos with TC tend to have a slightly warmer vape... simply, the heat source is closer to the mouth. Some feel that the flavor is better... perhaps because the vapor doesn't need to travel up a tube (a short trip though it is) to reach the mouth.
Filling from the top or bottom used to be more a separation... with BC clearos (of the Kanger style) mostly filling from the bottom, and TC's filling (not always here either) from the top. If this feature is important, read the fine print.