Regarding the request that B'nai Isra'el made to Edom,
וַיֹּאמְר֨וּ אֵלָ֥יו בְּנֵֽי־יִשְׂרָאֵ֘ל בַּֽמְסִלָּ֣ה נַעֲלֶה֒ וְאִם־מֵימֶ֤יךָ נִשְׁתֶּה֙ אֲנִ֣י וּמִקְנַ֔י וְנָתַתִּ֖י מִכְרָ֑ם רַ֥ק אֵין־דָּבָ֖ר בְּרַגְלַ֥י אֶֽעֱבֹֽרָה׃
And the children of Israel said unto him: ‘We will go up by the highway; and if we drink of thy water, I and my cattle, then will I give the price thereof; let me only pass through on my feet; there is no hurt.’
Here, they implied a possibility that they might drink water, and if so, they would pay for it.
But, in the request to Mav, it says:
אֶעְבְּרָ֣ה בְאַרְצֶ֗ךָ לֹ֤א נִטֶּה֙ בְּשָׂדֶ֣ה וּבְכֶ֔רֶם לֹ֥א נִשְׁתֶּ֖ה מֵ֣י בְאֵ֑ר בְּדֶ֤רֶךְ הַמֶּ֙לֶךְ֙ נֵלֵ֔ךְ עַ֥ד אֲשֶֽׁר־נַעֲבֹ֖ר גְּבֻלֶֽךָ׃
’Let me pass through thy land; we will not turn aside into field, or into vineyard; we will not drink of the water of the wells; we will go by the king’s highway, until we have passed thy border.’
Here, they say from the start, that they will not drink any water at all - )no offer to pay).
Why the difference regarding these two nations?