Brahma
Obi-Bro Kenobi-X
B series boards are lower end boards that have cheaper components and less features. Generally not an issue if you're not overclocking and don't need specific things, but you are getting a cheaper product that will usually have lower-end onboard sound, lan, USB etc... In the specific B board you linked the main thing that pops up is that its ram speed compatibility is super low. If you want to overclock at all, you definitely don't want a B series board. Note that the Z series boards come in many price points, so you have a lot to choose from that are cheaper than the one you linked.
That's good info. Never knew that.