These three are easy to confuse. The differences come down to what is added.
Purified water with no additives. Single-use, since it has nothing to inhibit bacterial growth once opened.
Sterile water plus about 0.9% benzyl alcohol, a preservative that lets a vial be used more than once within a limited period. Frequently chosen in research settings for reconstituting lyophilized compounds and peptides.
Sterile water with dissolved sodium chloride (salt), formulated to a specific concentration for particular uses.
The right choice depends entirely on the application and the compound being handled.
This article is for general educational purposes only and is not medical, health, or professional advice.