Below is a description of the various ID's found within reports.

Campaign Name Description
DonationID ID given for each donation that occurs
RegistrationID ID given for each registration record created
PaymentID ID Associated with a payment. There can be one Payment ID for several transactions (multiple donations and registrations)
Refunded PaymentID ID Associated with a refunded payment. When a refund occurs there will be a Payment ID and a Refunded Payment ID issues. 
Recurring Donation ID ID Associated with a recurring donation
TransactionID ID/code that comes back from the processor after a transaction. Similar to the Payment ID where it can be tied to more than one transaction (donation/registration) but indicates the transaction took place at one time.
Donor UserAccountID
DonorID ID associated with a donor. 
UserAccountID ID Associated with a useraccount. This is anyone in the system: donor, registrant or contact. This is different from a registrant or donor ID.
MemberID ID associated with a fundraiser.
GoalID ID Associated with a goal
TeamID ID Associated with a team
TeamGoalID Team's Goal ID
Donation To GoalID A Goal ID to whom the donation was credited. 
TicketID ID Associated with a ticket. 
StatementID ID given for each statement, or billing invoice, that goes out.
Global Member ID/Group Member ID ID given to a fundraiser that spans multiple campaigns and ties back to the client.