We previously reported that RO⁺ expression correlated with increased mutation, activation, and selection among human germinal center (GC) B cells. Here, we subdivided human tonsillar B cells, including IgD⁻CD38⁺ GC B cells, into different fractions based on RB expression. Although each subset contained RB⁺ cells, when used as an intrasubset marker, differential RB expression effectively discriminated between phenotypically distinct cells. For example, RB⁺ GC B cells were enriched for activated cells with lower AID expression. RB inversely correlated with mutation frequency, demonstrating a key difference between RB- and RO-expressing GC B cells. Reduced RB expression during the transition from pre-GC (IgM⁺IgD⁺CD38⁺CD27⁻) to GCB cells was followed by a dramatic increase during the GC-to-plasmablast (IgD⁻CD38⁺⁺CD27⁺) and memory (IgD⁻CD38⁻CD27⁺) transition. Interestingly, RB⁺ GC B cells showed increased signs of terminal differentiation toward CD27⁺ post-GC early plasmablast (increased CD38 and RO) or early memory (decreased CD38 and RO) B cells. We propose that as in T cells, differential RB expression directly correlates with development- and function-based transitions in tonsillar B cells. Application of this RB:RO system should advance our understanding of normal B-cell development and facilitate the isolation of more discrete B-cell populations with potentially different propensities in disease pathogenesis.