Registration Source
This indicates what the person was doing that resulted in the member registering. The list of possible values are: None, Donation, Order, Comment, Blog, Event, Appeal, InMemory, Fundraiser, Email, Poll, Newsletter, Manager, Post, Unknown.
Approval Status
When a member is added to a group, they go through a series of approvals in order to decide if the member can be added to the group or not. Values are: Pending, Approved and Rejected.