A R5 is the leader of the guild, he can manage the members (promote/demote/kick) and change the description and requirements for the guild.
R4 can also manage all R3 but can't manage any R4 or R5. They can also change the guild requirements or description.
R3 can manage R1 and R2.
and R2 can manage R1.
Note that if an R5 has been inactive for 5d, a take over countdown will start and at 7d any member can take the lead.