Desalination and softening of water are quite different terminology. Softening is used to reduce hardness which mainly caused by excessive Ca and Mg and their anionic pairs such as carbonates and sulphates.  Whereas, desalination commonly used to reduce excessive sodium chlorides and other chlorides.

Dear Mohammad,

Desalination of water (also called desalination or desalination) is a process that provides fresh water (drinking or rarely due to cost, usable for irrigation) from brackish water or salt (sea water in particular). Despite the name, it is rarely to remove the salts from the water, but, conversely, to extract freshwater.

The water softening is a method of treatment for reducing the hardness of water (due to the presence of alkaline earth metal salts: carbonates, sulphates and chlorides of calcium and magnesium). Thus, it is more appropriate to speak of water softening when applied to reduce water hardness.

With my best regards

Prof. Bachir ACHOUR

Desalination and softening of water are quite different terminology. Softening is used to reduce hardness which mainly caused by excessive Ca and Mg and their anionic pairs such as carbonates and sulphates.  Whereas, desalination commonly used to reduce excessive sodium chlorides and other chlorides.

Desalination is a process that removes minerals from saline water. More generally, desalination refers to the removal of salts and minerals from a target substance as in soil desalination, which is an issue for agriculture.

Water softening is the removal of calcium, magnesium, and certain other metal cations in hard water. The resulting soft water is more compatible with soap and extends the lifetime of plumbing. Water softening is usually achieved using lime softening or ion-exchange resins

From definition, we can see the difference between two terms.

Desalination removes minerals from saline water and refers to salts /minerals removal. Saltwater can be desalinated to get water consumption. The by-product of desalination process is salt.

While water softening is removal of calcium, magnesium (principally as bicarbonates, chlorides, and sulfates in water) and some metal cations from hard water. This soft water is more compatible with soaps, extends life of plumbing. The water softening is done by means of lime softening and some ion-exchange resins.

Soften water (depending on residual sodium carbonate %) in which calcium and magnesium are partly replaced by sodium, doesn't suitable for irrigation, as it causes development of alkali soils. 

desalination = salt removal (minerals) from e.g. sea waters

softening = reduction in water hardness by reducing the Ca and Mg and the carbonate to a limit necessary for your consumption.

i will advise Softening.

thanks,

If Mg and Ca are removed from the water (not only exchanged), it is a partial desalination of this water.