Essentially, swagged bullets are pressed into shape. To do so entails that the lead alloy (it's not pure lead) is relatively soft(er).
Cast bullets start off with lead being heated to turn it into a liquid which is then poured into a mould. The lead alloy can have any of a few different materials added to it to make it a harder final product. Too, various methods of hardening the bullet afterward can jack up the hardness a bit - sometimes quite a bit.
Cast bullets can be shot to higher velocieties tahn swagged due to their extra hardness.
Swagged bullet's velocity should be kept to about, around (sorta
) 100 fps or so. I usually keep them well below that. Fact is, the only swagged bullets I shoot anymore are .38 special HBWCs & at 700fps or so, they do anything you could want them to.
Casts are another whole country & can be driven (depending upon alloy, caliber, gas check or no & lube) past 2000 fps with excellent accuracy, etc. In handguns & larger bore rifles, with goodly sized bullets & decent bullet profile (that metplat thing), I see no reason for jacketed bullets at all for game hunting.
Self defense = different story altogether, but a hole straight through's still a hole straight through.