If you were asked to explain the difference between an air cleaner and an air purifier, would you be able to. Do not worry if you cannot answer, as you are probably the same as the majority of folks who do not understand the difference between the two. Briefly, an air cleaner will filter harmful particles from the air while an air purifier kills bacteria, mold and viruses. Although ionic air purifiers are called "purifiers," they are not strictly purifying the air as they unable to kill organisms. Instead, air ionizers are an air cleaner.