Construction is totally different. The xhaler uses a mechanical switch, that is easier for a person to change out if there is a problem. The SB uses an electrical switch, but it is rated for very heavy use. The SB is alot bigger around and heavier than the xhaler, it just feels very sturdy. I have a black SB, and a co-worker has an xhaler. I am very glad I chose the SB even with the size difference. In my opinion, the SB is the best and most durable
mod out there.
The switch on the xhaler is at the tail end of the unit and is small and sticks out (which can be depressed while in your pocket)
The SB has a recessed switch at the top end that would be near impossible to go off in your pocket. To me, this is the most comfortable place for the switch.
The xhaler does have a knob at the end that can be raise or lower the voltage, but IMO it is just another piece that can break or need replaced.
I hope I have pointed out some good differences without being too biased (GO SB)