From the comments here it seems like we've got a case of an overloaded term. Just like you need terms like "intramural" and "club" to differentiate the type of

From the comments here it seems like we've got a case of an overloaded term. Just like you need terms like "intramural" and "club" to differentiate the type of sports team to which you belong there seems to be a need for a common and well understood differentiation between book groups which are primarily social and which are geared toward analysis and/or study. The objectives of the two groups don't seem to mesh well at all so perhaps they are deserving of their own terms.