The practical difference? Hmmm ... let's try this. We assume that you will use a fixed amount of cells for the motor. For this reason we say its perhaps 10 cells.

1. The 3019-12 will turn a bigger prop than the 3019-10.

2. On the other hand, you can always use the 3019-10 with less cells to turn a certain prop compared with the 3019-12.

3. If you want some speed then take the 3019-10 to turn a smaller prop at a higher RPM. Whilst the 3019-12 will give you more thrust with a bigger prop.

I hope this helps.