Reputation
By giving members the ability to rank an individual post up or down your community becomes more
dynamic, self-moderates, and encourages quality contributions. Configurable by the administrator, a
member can click "+" or "-" on a post to give or subtract a point. Once a certain threshold has been
reached that post can be automatically hidden. Points are accumulated for a particular member giving
them an overall reputation rating as well.
Warn System
From the new warn system, moderators can make private notes about a member, contact the
member, and also take action on their account. Actions may include suspending their ability to post,
requiring all the posts to be previewed, or completely banning a member from accessing the
community. Moderators can choose permanent or time-based actions.
User rating doesn't appear to be documented. I see it as recognition of a forum member's overall contribution to the community, as recognised by other members. Hope that helps.