The late 1890s was a time when any difference could be used to sell your product. And this tradition carried on for some time.
On paper, the 2 are about identical, other than caliber. Some folks swear there is a noticeable difference in their effect on game, others don't see it.
The generally accepted reasoning today is that the .32 Special was intended to be reloadable with black powder and give better results than the .30-30. (twist rate, fouling, etc.)
The .32 Special is one of those old rounds that has not yet been fully abandoned, because it does work, and the rifles it came in are still popular. I don't know if it is still a currently offered chambering or not, sales of new .32SPecials have been ...weak..for ages, even when they were a regular catalogue item.
Ammo production is "seasonal" meaning it is not regularly produced (not in continuous production). When stocks reach a set "low", they tool up and do a production run.
There's no reason I can see for choosing a .32Special over a .30-30 today, other than you want one, or the rifle you want is a .32 and not a .30-30.
My Dad carried a Win 94 .32SPl as his deer rifle for many years, and it worked well. He didn't choose it because it was a .32, he chose it because he got a heck of a deal on the rifle from the original owner's widow ($20, and get it out of my house, please!) Used it for about a decade or so, until one season's sight in where it (for no identifiable reason) decided to shoot 6" lower than the lowest sight setting, at which point Dad decided he was in the market for another deer gun.
