From the tone point of view, I can't say I can hear much of a difference between the two - both have a body made of ash and an ovangkol neck, and only the fingerboard is different (tiger ebony in the fretless, wenge in the fretted). Both have identical sets of D'Addario Chromes on, and I play both through the same PJB combo (one at a time, haha!).
Although the fretted is a 2013 model and the fretless is from 2010, the differences in the body shape are very subtle, and probably have little impact on the sound itself. It's mostly the playing style on the fretless that makes the difference, wot wiv it not having them bleedin' frets making unwanted clanky noises...
I'm deeply in love with both the sound and the look of both.
Some more pics of the new baby:
Note the low B saddle minus the spring!