Ms. Princessdee vertical coils have the coil running up and down the polyfill, where horizontal sits below it. Vertical coils have more surface area, hence them being able to handle higher voltage. Horizontal give really great flavor with no th, or all th and no flavor depending on the volts and ohms. Vertical coils give balance. Best way to describe it is in sports terms. Horizontal coils are someone who either plays great defense, or great offense, but not both. They're exceptional at what they do, but can only do one thing. Vertical coils are the all around player who is good at all aspects of the game, but not the best at anything. Both have their place, some love great flavor, others love great th, and others still prefer both. 
