It makes a difference.
I bought a bunch of "Norton" brand sandpaper when this project started because... I was at Home Depot and it was there. I just ran out of the course (~150) grit stuff and had to go get more. I wasn't really happy with how often I was changing sand paper on the T-bar sanders. It seemed to start going bald in just a few minutes of use but i didn't really think much of it.
Man I went out and got me some real 3M sandpaper. The Norton stuff was a HUGE mistake.
You would think something like sand paper would be easy to get right. Not so it seams. The 3M stuff is going strong, easily outlasts the Norton paper by 3-5 times. Its a small thing but every time I have to put fresh paper on a T-bar its a 20 minute ordeal. Gotta peel and scrape the paper off and soak it in goo-gone to clean up. Then cut new paper and stick it on with 3M 77. Big wast of time.
Do yourself a big favor and seek out the 3M sandpaper. I found 3M it at Lowes but not Home Depot.
When you think about it, bad sand paper is a great scam. You just put some clever marketing on a box of crappy paper and wait for the customer to come back.
All my Norton paper is in the trash can. You couldn't pay me to use the stuff now. No more wasted time for me.
Another good trick is this
Abrasive Cleaning Stick. It can get the crud off the sandpaper, belt sanders, sanding disks and the like so they cut like new. This really helps when sanding foam which tends to clog the sandpaper