The primary difference isn't what you have to do (the security requirements are almost identical), but how the Regulator treats you:
· Essential Entities (Proactive): The regulator can audit you at any time just to check your homework, even if you haven't had a breach.
· Important Entities (Reactive): The regulator typically only shows up if there is "evidence" of a problem (like a major breach or a whistleblower report)