Apparently, due to the shape of the round ball being a sphere, it acts to compress the air more as it flies, which is amplified when the speed is increased...compared to a pointed, elongated bullet, often called a spitzer style bullet.
Another question is what you mean by "difference".
I was taught that without a bone impact, a bullet must impact at minimum 1050 fps to be "reliable" in deformation, and when it has decreased to below that, it pretty much stops deforming. The reason that I use less than absolute wording is because that's mostly based on what is seen with modern bullets, often jacketed, often soft tip or hollow-point..., but I've been told by a couple Forensic Pathologists that it holds true pretty much for soft lead bullets including round ball.
So technically, Dutch, the 80 grain load on the chart has a big difference to the 50 grain load, at 100 yards, since the 50 grain load is below 1000 fps at that range.
In my case my 70 grain load and .530 round ball start out at about 1500 fps, so my projectile is starting slower, and is fatter than a .490 ball so it sheds speed a bit sooner, and is likely under 1000 fps at perhaps the 70 yard mark, and maybe even sooner.
Which is why the caveat "You can only depend on the damage caused by the actual contact of the projectile with the tissue as it passes through the animal" rings so true with me, and I repeat it for hunters. Still.... a 1/2" hole, give or take a few thousandths of an inch, is a pretty big hole in a game animal. Seems to get the job done in a rather rapid manner.
LD