Thanks for the question.
The difference between a capital cost allowance and an accelerated capital cost allowance is that, with the latter, you can write off in three years what currently would take 14 years. If you're looking at development of a project in mining, where all of the costs are up front, keep in mind that companies have zero revenue stream relative to investment until they process and bring to market the first pound, ounce, or tonne of material that they've extracted from the ground. That means they're the most over-leveraged, from a cost investment standpoint, relative to revenue stream at the point of production.
If you look at how quickly it takes a company to recoup and become profitable after that investment, an accelerated capital cost allowance can accelerate and therefore improve project economics for projects moving forward.