For "older" bb, you have square, ISIS, Octalink, other, and none of them interchange with the other cranks, they are crank specific. With BB30 threaded, not press fit, do all cranks now finally interchange with threaded BB30 or are they specific such as FSA BB30 crank will not interchange with Shimano BB30 bearings.
As reptilezs said, bb30 is not threaded. I'll add that BB30 is a bottom bracket "standard." It is what it is. The bore in the frame is 42mm in diameter. The bearings are pressed into the frame, not threaded. A spindle for a bb30 crank is 30mm in diameter.
However, you can use many other types of cranksets in a frame that is designed for bb30, with the proper adapters. You can use a threaded sleeve that is pressed in and will then allow the use of conventional, threaded bottom brackets, such as square taper, ISIS, or Octalink, or even external cups. These press-in, threaded sleeves essentially convert a bb30 frame to a frame with a threaded bb shell.
You can use adapters that allow the large, pressed-in bb30 bearings to stay in the frame, and the adapters act as shims that allow the use of cranks with the common 24mm diameter spindle in place of the 30mm spindle diameter the bb30 bearings are designed for. These 24mm diameter spindles are used on cranks that would normally be used with external cups on frames with threaded shells.
Hope this info helps. For the record, I'm not condoning the use of any particular item I mentioned, just letting you know what's available-
One more thing: there's no such thing as Shimano BB30 bearings, because Shimano doesn't do BB30. But can you use in a BB30 frame, let's say, a modern Shimano crankset, designed for either threaded, external bb bearings or Shimano's own press-in bb bearing system, BB86? Yes.
The cranks will have a 24mm diameter spindle, so you can simply use Wheels Mfg adapters , the ones that act as shims like I mentioned in the above post, and then the BB30 bearings can stay in the frame and the Shimano cranks will work just fine. Or you could even use a press-in threaded sleeve like I mentioned above and then use external bearing cups with the Shimano cranks.
Also, best to source a BB30 bearing set from the same company that supplies the crank you want to use. For instance, Sram and FSA both have BB30 sets, but they are not interchangeable without some bodgering.