I tend to think of them as three different products.
A rendered beef fat is more like a lard, a commercially purified product, used for frying.
Beef dripping is traditionally the fat and meat juices from a roast; although in commercial situations, like a fish and chip shop, the “dripping” they use is rendere beef fat.
Suet as you say is a specific fat from the beast and thus had certain characteristics. It’s harder than rendered fat and thus can be shredded, which made it good for making pastries and doughs. And I think it’s melting point helps form the unique characteristics of suet pastry.
In the old days you could buy fresh suet from butchers but these days it’s packaged. The fresh suet would work as a general fat for cooking but packaged suet had flour and preservative to keep its granular texture so wouldn’t work.
