I am often asked how the Warr Guitar differs from the Chapman Stick. There are similarities in that the tuning can be the same (BEADGC C#F#BEAD is what I use) and they are both played using the touch style method. I still own my original Stick (seen below with one of my Warr Guitars) so in looking at the two instruments, it becomes clear that there are similarities in the overall idea.
The differences lie in the body construction and electronics. The Warr has two jacks for the melody and bass sides while the Stick uses a stereo cable that may be used in stereo or mono output positions. The Warr guitar uses a guitar strap and can be moved to sit in the vertical position or a more horizontal position. The Stick clips onto your belt and uses the arm strap to stay secured in the vertical position. The Stick uses an assortment of pickups (I have an active Block pickup) designed by Stick Enterprises. The Warr guitars used to use Bartolini pickups (pictured on mine below), but now use custom pickups designed by Pete Hanewinckel, the builder.
Personally, I like the feel of having the guitar body there. I also feel like the Warr Guitar adds sustain that I do not get with the Stick. Having said that, the Stick is convenient as it fits in a nice thin bag and can be transported easily.
Reach out if you are considering purchasing one and I would be more that willing to offer more insight. Thanks.