Essentially, cash accounting shows the real amounts spent in a year. Let us suppose that the government spends $100 million to build a building and construction takes two years. Using cash accounting, the $100 million would be shown as a cost in those two years. In accrual accounting, you have to show the amortized amount. For a building, amortization is normally somewhere between 25 and 40 years, so a twenty-fifth of the cost.
On February 10th, 2009. See this statement in context.