Generally speaking, the fewer teeth per inch on a blade, the larger those teeth tend to be, and the deeper the gullets. This means that with each stroke of the saw, a larger quantity of material is being cut and removed.
As a result, a blade with fewer, larger teeth per inch will cut much quicker than one with more teeth. However, because of this aggressive cutting action, there is a greater chance that the material’s fibres will become torn, creating a rough finish.