Pool filter sand is whiter and cleaner. I put directly into my tanks, but does cause some cloudiness, but the filter clears it in a day or so.
I should say whiter at first. It doesn't stay that way over the long term. It picks up color from plants...fish poo..etc.
And I mix mine with fluorite anyway.
Since I never really compared it to play sand, I don't kniow if the grains are bigger or not.