While researching tools in the quest to become a handyman, I was captivated by the fact that one of the top brands sells 54V (60V max) cordless power tools while another sticks to 18V. Two questions about electrical motor theory come to mind:

1. Is there any theoretical or practical difference between brushless motors at 18V and 54V to make one voltage design inherently better for one reason or another (torque, temperature, efficiency, etc).
2. If there are no/negligible differences between 18V and 54V motors, is there a DC voltage level at which the difference become significant in a non-theoretical way?