A sobor is distinct from a synod, which is a gathering composed only of bishops. Sobors are held irregularly, only as need arises; whereas a synod meets regularly and deals with the ordinary governance of the church. The presence of clerical and lay delegates is for the purpose of discerning the consensus of the church on important matters; however, the bishops form an upper house of the sobor, and the laity cannot overrule their decisions.
Important sobors in the History of the Russian Orthodox Church are:
A bishop may also call a sobor for his diocese, which again would have delegates from the clergy, monasteries and parishes of his diocese, to discuss important matters. Such diocesan sobors may be held annually or only occasionally.