What's the diff between horizontal & vertical coils in cartomizers for KR808-D1?

[wefishallday]

Been trying to decide on blank cartomizers with inner seals that I like for my 5 batteries -- all KR808-D1.
4 are 3.6V, 180mAh batteries from ST
1 is a 5V USB passthrough from ST

In reading the posts/discussions, people are talking about vertical and horizontal coils in the cartomizers. I figure that's the layout of the coil itself inside the carto but don't know why one is better than the other. Can someone explain this? Thanks for any help you can give

 

[Goldenkobold]

The horizontal coils
like this one

Have a heating element at the bottom and that element is for the most part not in direct contact with the polyfill absorbent material...

the other more common design is

which has less wick dependent elements but has more contact between heating element and pollyfill