Quick take
Choose between them based on verified feed-water limits, service flow, warranty and installed cost. Neither should be marketed as equivalent to ion-exchange softening.
What both systems do
Both use salt-free conditioning rather than removing calcium and magnesium from the water.
Feed-water limits matter
Conditioning media can have strict requirements for iron, manganese, sulfur and other contaminants. Well-water users often need pretreatment.
Maintenance advantage
No salt and no regeneration can simplify ownership compared with a conventional softener.
Who should not buy either
If the goal is slick-feeling true soft water, measurable hardness removal or maximum soap efficiency, use an ion-exchange softener instead.