Jims pretty much on the money, they are both made of lead, but commercially cast bullets are usually harder than the swaged lead like the Hornadys. Both have their place, but if you are intending on anything other than plinking loads, the hard cast will usually be a better bet than the softer ones which will tend to lead tha bore more if shot at any speed over 800 to 1000fps. in my experience. I cast my own, and shoot some at 1800 fps. with no problems. Again, it's all in what you want to do.