Batman and Robin.  Dr. Evil and Number 2.  Snooki and JWoww.

Every successful relationship needs a leader and a loyal, trusted sidekick.  This is how the online community manager and the moderator work together to build a healthy community and rid the world of trolls (usually without laser-mounted sharks or self tanner).

Sometimes, the lines are blurry, as when a community manager also does moderator tasks, or when a team of moderators takes the place of a single community manager (this is not recommended).  

How can you put in place a workable system that respects the individual strengths and responsibilities of each role?  Here are some general guidelines (your situation might require something different):

Community Manager

• Sets up community guidelines and terms of service
• Develops membership outreach programs
• May support the social media manager or marketing lead
• Conducts analysis and reports up the chain
• Manages disputes that moderators can't resolve
• Facilitates integration of community with overall social media plan
• Recommends platforms and social tools
• Performs monitoring for brand mentions and opportunities
• Helps to promote and represent the community
• Represents the community's voice within the organization

Moderator

• Screens new registrations, welcomes new members
• Supports the organization of topics
• Mediates disputes among members
• Reports up the chain if there is a larger issue brewing
• Sometimes has power to ban unruly members, otherwise reports up
• Fosters a healthy atmosphere
• May help create content or elicit member-generated content
• Ensures that community guidelines are being honored
• Performs "cleanup," deleting spam and content that violates the guidelines
• Acts as the face of the organization (but may or may not be paid)

Generally, the community manager is the planner and the moderators are the implementors.  In an ideal community, there is a lot of cooperation between the two roles, and clearly delineated responsibilities. 

How is your community management structured?