Hi @Annabelle -
Both of those represent baseflow in a different way. qb is the mean baseflow within the watershed(s) or sub-watersheds you supplied as inputs. B.tif is the total amount of baseflow contributed by each pixel. So these values are given at very different scales (mean of watershed versus total from pixel.) These are briefly described in the User Guide Interpreting Outputs section.
Of note, all of us at NatCap are technically on winter holiday through 1/3, so we won’t be responding to the forum much during this time.
~ Stacie