There is a meaning actually. The numbers are the model lines, you can find them on their website. The B denotes the newer line of knives sporting the button lock. The T knives sported a liner lock and are no longer in production. The E knives are part of their "EDC" series, started by the E6 and E10, which are their lower cost knives with anodised alunimium handles.
The GenTac used to be called the G30, I'm not sure why, but it seems it has been given the B designation now too. They also made a friction folder, which I believe was given the H designation.