Well, there are a couple differences to think of.
1. The higher range in battery power alone extends the usable service life of the batteries you use. 3.7, 5.0, 6.0, 7.4,etc... While the battery is in use, it takes longer to run the battery down depending on your style of
vaping. If your are a heavy vaper who likes to take long and strong drags while you vape, then you are most likely to run through a battery quicker anyway.
2. The higher you go in the rating for your battery mod, the hotter the vape will be. For those vapers that want the most adverse throat hit, along with a little more kick from comparable heat given off ffrom an analog, the higher battery ratings emulate this.