天壤之別

天壤之别
tiānrǎngzhībié
  1. lit. the difference between heaven and earth (idiom)
  2. fig. night and day difference; a world of difference; a far cry (from)

CEDICT

to be poles apart; to be like night and day; to be a world of difference between them

Wiktionary

天與地相隔很遠。比喻差別極大。清．吳喬《圍爐詩話．卷四》：「以視其『柳塘春水漫，花塢夕陽遲。』有天壤之別，應酬之害詩如此。」《兒女英雄傳．第三六回》：「不走翰林這途，同一科甲，就有天壤之別了。」也作「天壤之判」。

重編國語辭典

天與地相隔很遠，差別極大

維基詞典

Entry Composition

1 天 tiān
  1. day
  2. sky
  3. heaven
2 壤 rǎng
  1. (bound form) soil; earth
  2. (literary) the earth (contrasted with heaven 天 tiān)
3 之 zhī
  1. (possessive particle, literary equivalent of 的 de)
  2. him
  3. her
  4. it
4 別 bié
  1. to leave; to part (from)
  2. (literary) to differentiate; to distinguish
  3. (dialect) to turn away; to turn aside; to avert (one's face, gaze etc)
  4. (bound form) other; another; different
  5. don't ...!
  6. to fasten with a pin or clip
  7. to stick in; to insert (in order to hinder movement)
  8. (noun suffix) category (as in 性別 xìngbié, 派別 pàibié)