In the time of Haman, we concluded the gezerah was from Ha-Shem, as it covered all the Jews, and we responded by davening, fasting and learning.
Inthe time of the Misyavanim and their Greek allies, since the gezerah was only against Torah (the Greeks loved Jews who gave up mitsvos), we concluded that couldn’t be from Ha-Shem, and responded with “this world” sorts of actions.