In Parshas Bo ([12:8][1]) it says about the Korban Pesach:

>וּמַצּוֹת עַל מְרֹרִים יֹאכְלֻהוּ

but by the Parsha of Pesach Sheni in Bamidbar ([9:11][2]) it says:

>עַל מַצּוֹת וּמְרֹרִים יֹאכְלֻהוּ

Why the Change in the Language?


  [1]: http://www.mechon-mamre.org/p/pt/pt0212.htm#8
  [2]: http://www.mechon-mamre.org/p/pt/pt0409.htm#11