Resound Alera 9 vs. Resound b 9

I noticed in the Hearing Revolution website that the Resound Alera 9 and the Resound b 9 hearing aids are offered at the same price, although it seems the b 9 has fewer features than the Alera 9. I have been trying to learn more about the differences in both, but most of what I find has to do with the Alera 9. Does anyone know about the b 9, and what information can you provide? I am ready for my first-ever fittings and want to feel comfortable that I am making a wise decision. If my audiologist offers one of these two models over the other, is there anything I need to know? Thanks for any information