Why in connection with Aharon - in Pasuk 2, did the Torah write "Vata'al ha'Tzefarde'a" and here "Vaya'alu ha'Tzefarde'im"?
Seforno: Because, whereas with his staff, Aharon produced a crocodile that was able to reproduce, the Egyptian soecerers were only able to bring up frogs that already existed, but not to produce new ones.
What caused Pharaoh to suddenly acknowledge Hashem?
Seforno: When he saw the difference between Moshe and Aharon, who produced living crocodiles, 1 and his magicians, who could only produce lifeless creatures that resembled crocodiles, he acknowledged Hashem's superiority over his magicians. 2
We may infer this translation from Seforno's comments to 8:11; refer to 8:11:1:1, and also to 7:26:1:1*.
Refer to 7:23:1.1:3 and its note.
