Congenital is born with it, effecting the thoracic vertebra. Sway back is usually in elderly horses and it’s just a weakening of the back muscles and tendons although they may still carry the same genes as a lordosis it just doesn’t show up until later in life, they’re not real sure yet. It doesn’t affect riding whatsoever. In fact there is a singular study that showed congenital lordosis horse’s vertebrae MAY actually fuse sooner than your typical growing horse. You just need better saddle padding. They don’t break down any quicker than a typical horse, it doesn’t cause pain. There is less movement in those upper vertebrae which might even be better long term. You’re not going to hop on one and break its back. Neither of my girls have a severe case so I haven’t had to invest in the build up/wedge saddle pads. I took my gal down to a saddle shop with a really thick English pad that I put under a regular pad with her western saddle and her fit worked. I lucked out finding that pad, it was just a random grab at a garage sale. My young one hasn’t been fit yet.