Both are two different Mediums .In Facebook one can choose Groups of one's own Likings . Which is here in RQNA is just not possible .There are many groups with divergent interests From Political discussions to Cookery . From Cosmology to Cooking .In those groups one can interact at his/her own Will .On FB one can share many things which are not feasible here .
If someone do not like others , They have one facility of Blocking That Person , which We do not have here
Actually RQNA and FB are not Comparable .Both have different perceptions and backgrounds .RQNA Type questions one can ask there ,but the Features of FB can not be available here .