Purifiers remove viruses in addition to bacteria, parasites, microplastics and turbidity (silt, sand and cloudiness) and filters remove the above contaminants with the exception of viruses. The absolute pore size of LifeStraw membrane microfilters are 0.2 micron, whereas our purifiers have an absolute pore size of 0.02 micron (ten times smaller). Because of their smaller pore size, purifiers can remove virus, but they also tend to require more pressure or have a slower flow rate because of the smaller pore size.
Filtration and purification is the same as the difference between microfiltration (filtration) and ultrafiltration (purification). Microfiltration removes bacteria and parasites and ultrafiltration also removes virus.