Trane TZEMT400AB32MAA vs. TZEMT400BB32MAA

Hi,

I’m integrating my home security solution (which supports Z-wave) with my thermostat. My security company is recommending this Trane: TZEMT400AB32MAA. But I can only find the TZEMT400BB32MAA.

Does anyone know what the difference (if any) is between these two models of Thermostats?

Thanks,

Brian