Major league baseball
The difference between an actual, “official” Major League baseball – game ready – and any other lesser-league baseball is fairly noticeable.
This is the official Major League baseball:
The left one, signed by Allen H. “Bud” Selig as commissioner, is a 2014 ball. On the right, signed by Robert D. Manfred (Jr.) as commissioner, is a 2019 ball.
One can feel a difference between the two, primarily in terms of hardness. The 2019 is incredibly hard, with as much give as a solid granite stone. An even better illustration is the 2017, 2018, and 2019 balls are compared:
They’re labeled as “Spring Training” balls, but this signifies to us (as umpires and staff) that they are for use for Major League and AAA pitchers within the spring training time period of that year. AA and A league players use a different ball (pictured below), while international league players (such as Korean Professional, Mexican Professional, or Japanese Professional) will bring and use their own ball. I’ve called games wherein, at any one time, I’ve got one of four different baseballs in my ball bags.
Here’s a better, closer view of the three latest Major League baseballs (I didn’t get a 2020 ball, because, obviously, COVID-19 stamped out the season):
Look, specifically, at the seams. The threads on the 2019 ball are finer, and the gap in the seam is much tighter. Why’s that? Because between the 2018 and 2019 seasons, Rawlings (which is 50% owned by MLB) undertook a substantial quality controls campaign in the production of Major League baseballs. The rubber-clad cork pills (the center core) was made more precisely, the winding of the yarn was done, robotically, more precisely, and the leather casing pieces were precision cut by a laser. The stitch holes were also “shot” more precisely by a laser-guided machine. As such, the entire ball was made “tighter”. To whit, this tighter ball brings with it a degree of fragility. The entire ball is so tight the seams look like they’re under enormous tension, and are on the verge of splitting.
This fragility isn’t a problem when the average lifespan of a Major League baseball in a game is less than five pitches. However, these baseballs, once removed or rejected from a game, are not to be used for a game again, and are actually too hard, too slick, and too tight to be used in pitching machines for batting practice. They can be used as Live batting practice balls, and while some do end up being acquired by amateur organizations, I can speak from experience, they don’t hold up as well as their Minor League or lesser-league siblings:
In the upper left is that same 2019 Major League baseball. In the upper right is the “Generic” Minor League Baseball (this one is not labeled with the specific minor league, thus, any AA or A club may use it). In the lower left is the Arizona Fall League (Rookie League) baseball. In the lower right is the “Rawlings Official League Baseball” (which was asked about in the OQ). This particular one is labeled for use by the Dutch professional league (KBBSF•FRBBS). Note how much thicker and more robust the seams are both the AZFL and ROLB baseballs. These baseballs are similar to the specification used for High School (NFHS) baseballs. Each conference in NCAA & NAIA baseball is allowed to designate their own baseball, too, but nearly all are using the same specification found in the Minor League baseball. It really is easier on a pitcher to pitch than its Major League sibling, and tends to hold up over multiple pitches, hits and impacts better. One of our NAIA conferences here uses this type of baseball, and provided the players & staff-members retrieve the foul balls, we use no more than 12–16 of them per 9-inning game.
Most of our Adult Amateur leagues use the same spec as the Minor League ball. Some of the local (to Phoenix, AZ) leagues even go so far as to obtain “used” baseballs from the fifteen clubs that call Phoenix home, and I can tell you, hand on heart, the Minor League balls last longer than the Major League ones, besides the pitchers find the Major League ones too hard, and the seams too low, to get good bite on curves and sliders on.
“What is the best ball to use for fun to shag and hit some homers?”
Any, really, that are 9-in circumference, 5 oz in weight, and are a cork-&-rubber pill encased in yarn and leather. There really isn’t any difference in terms of hitting; the difference is in terms of durability and pitching.