B stands for the Second generation of Scoutguard products. It is associated with
the second generation of DSP, which is a short name for Digital Signal Processor.

New product releases this year are all B models. Additionally, there might be other symols like V, M, P, F, each of which characterizes a prominent feature. For example, V stands for Color Viewer, M stands for mobile connection, P stands for Professional Grade, F stands for (white) flash.
These symbols may be used together, like the 560VB model. B is typically omitted if the same ID has no A (non-B) model.