雲泥の差

Phrase composed of 雲泥 (undei, “clouds and mud”) +‎ の (no, possessive particle) +‎ 差 (sa, “difference”).^[1][2][3][4] Compare Chinese 雲泥之別／云泥之别 (yúnní zhī bié), 雲泥之差／云泥之差 (yúnní zhī chā, “difference between clouds and mud: a stark difference”).

The full Japanese phrase is first cited to a Christian work from 1592.^[1] The term 雲泥 (undei, “clouds and mud”) is used on its own in Japanese as a metaphor for a marked difference in citations as early as roughly 900 CE.^[5]

• (Tokyo) うんでーのさ [ùńdéé nó sá] (Heiban – [0])
• IPA^(key): [ɯ̟̃nde̞ː no̞ sa̠]

雲(うん)泥(でい)の差(さ) • (undei no sa) 

1. [1592] "the difference between clouds and mud": as different as night and day; a great difference when compared with the same scale, one being far better than the other

   Synonyms: 雲泥万里 (undei banri, literally “clouds and mud, leagues apart”), 月と鼈 (tsuki to suppon, literally “the moon and a soft-shelled turtle”)

   Antonym: 大同小異 (daidō shōi, literally “big same little difference”)

   • 1906, Natsume Soseki, Botchan:

     今(いま)まで物理学校(ぶつりがっこう)で毎日先生先生(まいにちせんせいせんせい)と呼(よ)びつけていたが、先生(せんせい)と呼(よ)ぶのと、呼(よ)ばれるのは雲泥(うんでい)の差(さ)だ。

     Ima made butsuri gakkō de mainichi sensei sensei to yobitsuketeita ga, sensei to yobu no to, yobareru no wa undei no sa da.

     Up to now, in Physics School, I'd called out "professor, professor!" every day, but calling someone "professor" and being called "professor" myself was as different as clouds and mud.