These values represent the different types of Revenue.

Gift = Donations
Matching Gift Claim = Matching Gift Claim
Matching Gift Payment = Matching Gift Payment
Pledges = Pledge
Pledge Payments = Payments to Pledges so Pledge payments
Recurring gift payment = payments to Recurring gifts
Event registration fee = payments towards events
Planned gift = planned gift records
Planned Gift Payment = planned gift payments
Membership = payments towards memberships
Admission = (I believe this should not be showing and may be a revenue type for Student Billing functionality that would typically have to be unlocked.  This also isn't release yet)
Other = All other revenue record types.

These shouldn't be confused as having a one to one relationship with Transaction types as there is additional functionality going on in the coding of the smart fields that classify each revenue payment as one of the above.  Typically it's pretty straight forward in regards to what each one pulls.  For instance Gifts would be all straight up donations.  Match gift claims or payments are those types of transactions and payments.  Same for pledges, recurring gifts, and planned gifts. 

As for fields that would exist on the revenue records themselves, these don't exist due to these types representing gifts and being calculated as whichever type directly in the smart field logic.