We sell both boards.
In general, the Spectrum has a little more round tips, the NBL is slightly more square and has 1 centimeter larger fins. Otherwise, they are very comparable. Before the 2013 models, The Cabrinha boards were very average and we strongly favored Nobile. Now the Cab boards are much better. I still prefer the Nobile on the high end. But as a good, general, affordable, all around board, the NBL and Spectrum are pretty close.
Thanks,
Stafford
www.adventurekiteboarding.com