Prednisone has to be metabolized by the liver to its active form prednisolone.

In US, Upjohn patented prednisone as Deltasone many decades ago, and that became the preferred form here for humans by habit.

But Vets use prednisolone for most animals, and especially cats, who cannot convert prednisone well to the active form.

Upjohn also made methylprednisolone aka Medrol and patented that, which is still used commonly here for inflammation and transplanted organ rejection prevention. The Medrol Dospak is a carded taper the patient can easily punch out daily for correct use. It is still very common here.

Prednisolone is still used in other countries however for humans.
Here in US it is becoming difficult to find in pharmacies now, which I discovered when our cat Oreo needed it for her cancer chemo. Two pharmacies told me they couldn't even special order it, so we HAD to get ours from our Vet.