Respirators are normally certified and tested by NIOSH and will be marked with an approval rating (N95, N100, etc). Disposable Face masks are generally looser fitting while respirators are tighter and need to be properly fitted by a professional to make sure it is worn correctly. Normally respirators will be labelled as such on its packaging or even on the respirator mask itself. Respirators also feature stronger filtration compared to other types of face masks. Respirator masks may also have a visible valve on them, though that may differ depending on the rating or manufacturer.