You read about both and it sounds like why am I carrying those bags of salt? Be careful do your research completely. Do not stop at what you want to hear. First let’s explain how they work.
A softener that uses salt has an ion exchange process. This means as the water passes through the resin one calcium ion is exchanged for one sodium. The calcium sticks to the resin bead and does not enter your plumbing coming into your house. When the resin beads are coated in calcium and can no longer hold any more calcium the unit goes into regeneration.