Sterile water and bacteriostatic water are both used in medical and pharmaceutical settings, but they serve different purposes due to their distinct properties:

STERILE WATER 
Sterile water is purified, distilled water that has undergone a rigorous filtration and sterilization process to remove impurities and microorganisms, making it entirely free of bacteria, viruses, fungi, and other contaminants.
It is typically used as a diluent for medical procedures like wound cleaning, irrigation, and humidification.
Sterile water is meant for single-use and does not contain any additives to prevent the growth of bacteria over time.
It is not suitable for extended storage because it lacks a bacteriostatic agent

BACTERIOSTATIC WATER
Bacteriostatic water is also sterile and purified water, but it includes a bacteriostatic agent, typically benzyl alcohol, at a concentration of 0.9%.
The bacteriostatic agent in bacteriostatic water prevents the growth of bacteria within the water for an extended period, typically up to 28 days after opening the vial.
It is used for reconstituting medications, especially those intended for using more than once.  
The presence of the bacteriostatic agent helps maintain sterility and prevents contamination of the medication.
Bacteriostatic water is not meant for injection directly into the bloodstream.

Bacteriostatic Water (bacteriostatic water for injection) is sterile water containing 0.9% benzyl alcohol that is used to dilute or dissolve medications; the container can be reentered multiple times (usually by a sterile needle) and the benzyl alcohol suppresses or stops the growth of most potentially contaminating bacteria. The Bacteriostatic Water can be used in diluting drugs that can subsequently be administered by intramuscular, or subcutaneous injection.