ה וּבִמְלוֹאת ׀ הַיָּמִים הָאֵלֶּה עָשָׂה הַמֶּלֶךְ לְכָל–הָעָם הַנִּמְצְאִים בְּשׁוּשַׁן הַבִּירָה לְמִגָּדוֹל וְעַד–קָטָן מִשְׁתֶּה שִׁבְעַת יָמִים בַּחֲצַר גִּנַּת בִּיתַן הַמֶּלֶךְ
5. And in the filling of these days, the king made for the whole nation found in Shushan the capital – from the great to the small – a party seven days in the courtyard of the garden of the king’s house.
Assuming that the seven day party was separate from the 180-day party, and not just the last week of the former1, Rabbi Dovid Feinstein notes that the king would have needed to serve as much food or more in these seven days than in the entire feast since the longer feast was only for dignitaries, as noted above, whereas this feast was for every inhabitant of Shushan – a far larger group. Therefore, the Megillah uses a quantitative term instead of a qualitative one in order to emphasize the sheer amount of food an drink available.
1Although there is some contention in the Midrash (Esther Rabba 2) regarding this point, I would also humbly suggest that the “psik” cantilation mark after the Hebrew word suggests an end of the 180-day party.