A
ballast box is just a heavy thing on your 3pt hitch. A box blade is heavy. Generally they will ge around the same weight. A ballast box is thin steel you fill with dirt, a box blade is heavy steel with no way to fill it with anything. Some people do strap logs or heavy steel bars ontop of a box blade for more weight, but that often puts the box blade beyond its strength capacity.
I built a ballast box & used it maybe twice in 8+ years. It's more compact than other impliments, which is its only value. Handy if you operate in tight areas, but not worth putting on if you are operating the open & have any other impliment on. I just leave my box blade, mower, LPGS, or snowblower on the rear & it ballasts as well if not better than a ballast box.
Always make sure you have proper ballast on the rear & are in 4wd when using the loader. I had a 150lbs gate on the pallet forks, no ballast, no loaded rears & was in 2wd on my old L3200 (Same machine as your L2501). Going down a slight hill the rears lost traction & I put a pair of pallet fork sized holes in the back of the barn. No brakes on the front unless you are in 4wd & no traction on the rears without ballast.
If you lift omething to heavy on the loader with ballast, it won't lift. If you lift something to heavy without enough rear or tire ballast the rear axle comes off the ground, the front axle flops to one side (its just a single pin, nothing else) and the machine rolled over. If in doubt always have excessive ballast. It will save your life & your machine.
SSQA is the quick attach on the loader. AQuick Hitch is something for the 3pt. You'd put pallet forks or a bucket on a SSQA on the loader. A box blade would connect to a 3pt or Quick Hitch. A Quick Hitch makes changing impliments faster, but doesn't fundamentally change anything. If something fits on a QH, it will fit on a standard 3pt. A SSQA impliment will not interchange with a pin on bucket or pallet forks though. If you didn't get a SSQA loader it will be very expensive to convert things or take half an hour & a sledge hammer to change impliments. To go from a 3pt to a quick hitch takes $200 & 15 minutes, trivial to add on later.
A box blade has plates on the side of the blade & moves dirt forward & back. A back blade has no end plates & can be angled to either side. A box blade is a heavier impliment for moving dirt & rocks. A back blade is a light duty impliment that weighs less. It's for moving snow, unpacked gravel or dirt.