While oftentimes the words mildew and mold are used to mean the same thing, there are actually some key differences, primarily how to get rid of them. Both mildew and mold need three things to survive and thrive, including a wet or damp environment, a "food" source like the glue underneath vinyl floors or the paper behind sheet rock, and a temperature over 40°F. If temperatures are colder than 40°F, then mold will go into a dormant state and survive until the conditions are suitable.
Mildew is that grey or white stuff you see in the shower or other area that routinely gets wet, like around the bottom of your windows from condensation. Mildew grows in a flat pattern and appears either powdery or fluffy and it is overall harmless and relatively easy to clean with bleach or other cleaning agents. Mold though is generally black, green, or yellow and may be slimy and smell. Black mold especially is dangerous and can make you very sick, with some health complications being permanent, lasting long after a person is no longer exposed to that environment. Mold removal protocol exists because proper mold removal is complicated since mold spores are invisible and if released into the air, the spores can travel via your air ducts throughout your home.
If you suspect your property needs mold remediation, call a professional to ascertain the correct procedure to handle the mold damage removal, including sealing off non-affected areas and air ducts so that there is minimal movement and spread of the spores. A professional can also determine what the water source of the problem is, enabling the water source to be eliminated and thereby preventing mold damage in the future.
So now you know that you can safely clean that mildew in your shower and that you should not try to clean the slimy black or green mold growing in your basement. Call the professionals to do an air quality test to help initially diagnose any suspected mold issues as the methods of mold removal will vary depending on various factors and then eliminate at least one of the three things mold needs to thrive and future problems should be prevented.