במדבר פרק יד, ו
יְ הוֹשֻׁעַ בִּן-נוּן וְכָּל ב בֶן-יְפֻׁנֶה מִּן-הַתָּרִּ ים אֶת-הָּאָּרֶץ קָּרְ עוּ בִּגְד יהֶם:
מסכת תענית דף יד/ב
ר' אלעזר לא הכל בקריעה ולא הכל בנפילה משה ואהרן בנפילה יהושע וכלב בקריעה משה ואהרן בנפילה דכתיב ויפל משה ואהרן על פניהם יהושע וכלב בקריעה דכתיב ויהושע בן נון וכלב בן יפנה קרעו בגדיהם
Moshe & Aharon “fell on their faces” while Yehoshua and Calev tore their clothes. The petition of “falling on one’s face” is a lesser form than the petition of tearing one’s clothes. Therefore, one who is closer to HaShem, would need only to plea with a lesser format. Since their status was not the same, Moshe & Aharon (who were closer to HaShem) prayed by “falling on their faces”, while Yehoshua and Calev employed the stronger form of prayer of “tearing their clothes.” (One opinion is that Yehoshua and Calev did both forms of supplication).
Later after the death of Moshe, Yehoshua rose to a position equated with Moshe, and “falling on his face” was a sufficient petition (similar to the concept that a leader like Yiftach in his generation is equated with Shmuel in his generation). See Yehoshua 7,10, where G-d asked Yehoshua why didn’t he fall on his face, implying that action alone (and not tearing clothes) was enough for him at that time in that position of leader.
One should understand that the above differences apply when one is petitioning on behalf of the congregation. However, when the congregation is petitioning, they need only use the format of “falling on their faces”, since additional merit is not needed. Also, when one petitions on one’s own behalf, then “falling on one’s face” is sufficient (per O.C. 131)
