Reading the sites, the process is the same to produce both, only the leaf used is different. FVF is Virginia, of course. I always thought to Best Brown as a Virginia. But the the descriptions say it is, or was, hand stripped, flue-cured Zimbabwe leaf. What the heck does that really mean I wonder? A Virginia variety or a burley variety?
FVF to me is indeed rich, without a hint of sweetness while BBF also has some richness but also some sweetness, (haven't found it particularly "haylike"). Lately I've found myself favoring BBF as I find I prefer the sweeter taste, but they're so close in my preferential scheme that that can change by the day. earl