Revenue Types are broader categories for your pledges, payments, and orders. For example: a pledge and a pledge payment are both considered a Gift
Transaction Types
PaymentPayments are the checks, cash, and credit card charges your organization collects.
OrderOrders are collections of  items that a patron purchases via a Sales Method (Daily Sales, Advance Sales, Group Sales, or Online Sales)
Pledge, Recurring Gift, Matching ClaimPledges, Recurring Gifts, and Matching Gift Claims are promises that constituents make to make a payment for a gift. Often times these are paid at a later date.

Applications help us to tell where that payment, order, or pledge is going. For example: if you check membership beneath payment, your smart field will be counting membership payments. 

Here is are example images of two common settings under Transaction type/Application for donation revenue: 
  1. Payments Received Only: This first example counts payments received only. Note: We recommend selecting Donation under Order to count any donations received via Daily Sales, Advance Sales, or Online Sales. User-added image
  2. Pledges and Commitments: The second example counts initial pledges and commitments, but does not count any payments on the pledges or commitments. ​​Note: We do recommend counting recurring gift payments instead of the initial recurring gift commitment. The ongoing payments are more reflective of the constituent's giving. User-added image