Ya know, I once had a NFP publisher explain the difference between for profit accounting and NFP accounting in a very succinct way. For profit accounting focuses on revenue and profitability. NFP's focus on how they spent donor's money.
That's why requisition management systems bring such value into the NFP environment. They can get better insight into budgetary spending by quantifying pending requisitions, approved requisitions, and purchase orders. This is similar to encumbrance accounting used by many municipalities.