I'm not sure there's a quick answer, but I'll try.
When you're looking at the narrative in the RPPs about changes in planned spending versus actuals, if a department had been planning to spend $10 on a program on which they spent $8, and they're supposed to spend $10 every year, but all of a sudden you notice they're spending $12 next year, the explanation is key. One of the explanations could be that they didn't get their ducks lined up that year. They couldn't spend what they thought they were going to spend and they reprofiled it to another year. It happens a lot with infrastructure programming.
The explanation in the narrative is key to understanding why that is. If you see a bump in program spending, up or down, it could be because there's been new money added, or it could simply be because a department was unable to spend or realize their plans and they've got permission to move that money to a new fiscal year, which requires Parliament's approval every year. The narrative is the key.