The texture of the twist is basically more irritating. Because of this, a horse is more likely to respond to applied pressure. This isn't necessarily a good thing though.
If you grab a smooth snaffle with one hand, and a twist with the other hand, you can imagine what each bit must feel like in the horse's mouth. A smooth snaffle is more comfortable to hold, but you could still feel it if someone pulled on it. The edges of a slow twist may bite into your hand a bit, and will create pressure points if pulled hard, so you may feel obligated to give in to the pressure if someone pulled on it. This is why horses are more likely to respond to a twist, and may seem more sensitive in one...
But this creates a false sense of responsiveness. The horse is still resistant to the rider's direction. They are just forced to give their head due to discomfort in their mouth. In time, a horse can get used to the feel of the twist, and can learn to tune out this discomfort. If this happens, then you'll be back to square one, and on the hunt for a harsher bit. It can become an endless cycle of changing bits, and it can become a struggle to find a bit that the horse hasn't learned to evade.
If your horse is unresponsive, or resistant to your aids, you need to find and resolve the root of the issue. Generally, a horse that won't bend or turn is tense or in pain somewhere. If it hasn't been done within the last six months, have a veterinarian or equine dentist check your horse's teeth, and have a professional saddle fitter check the fit of your saddle. If those two things don't pan out, a visit from an equine chiropracter and/or massage therapist might help. Then you need to take some riding lessons from an instructor who can teach you to ride more with your leg and core and less with your hands. There are ways that you, as a rider, can help your horse relax, loosen up, lift their back, bend, and turn, without even touching their mouth. There are methods of training that can lighten a horse that his heavy on the hands or resistant to aids. You just need an instructor that can help you figure it out on your own horse. French classical dressage is great for this. It doesn't matter what discipline you normally ride, every rider can benefit from basic dressage skills.