The rate of spool is also not linear. Two turbos could reach the same peak pressure at the same rpm with one reaching 4 psi at the throttle tip in very quickly and the other producing that 4 psi a few seconds later. Both could reach the same peak pressure at the same rpm however.
The turbo that produces positive more quickly will feel as though it spools much faster but show the same peak value at the same peak pressure as other turbos. The turbo that produces positive pressure more quickly will usually be a tad faster in everyday driving especially in situations like lane changes or pulling away from a stop light. It also helps in racing situAtions where you have to hold a line.