Why are there different phrasings of Korban Pesach accompaniments?

Question

In Parshas Bo (Exodus 12:8) it says about the Korban Pesach:

וְאָכְלוּ אֶת-הַבָּשָׂר, בַּלַּיְלָה הַזֶּה: צְלִי-אֵשׁ וּמַצּוֹת, עַל-מְרֹרִים יֹאכְלֻהוּ.

And they shall eat the flesh in that night, roast with fire, and unleavened bread; with bitter herbs they shall eat it.

but in the Parsha of Pesach Sheni in Behaalosecha (Numbers 9:11) it says:

בַּחֹדֶשׁ הַשֵּׁנִי בְּאַרְבָּעָה עָשָׂר יוֹם, בֵּין הָעַרְבַּיִם--יַעֲשׂוּ אֹתוֹ: עַל-מַצּוֹת וּמְרֹרִים, יֹאכְלֻהוּ

in the second month on the fourteenth day at dusk they shall keep it; they shall eat it with unleavened bread and bitter herbs;

Why are these two commandments phrased similarly but differently, with the first one apparently indicating a tighter coupling between the korban meat and the matza?

Answer 1

Maybe because there is no independent Mitzva to eat Matzo on Pesach Sheni. One eats matzo only to accompany the Pesach, identical to the mitzva of Maror.

Whereas on Pesach Rishon, there is an independent mitzva to eat matzo, besides the requirement for it to accompany the consumption of Pesach.