be as far apart (/as different) as heaven and earth; a world of difference ❍ 比起先前用皂荚时候的只有一层极薄的白沫来，那高低真有～。(《鲁迅选集》上—128) The difference between these and the small white bubbles produced by honey locust pods was like that between heaven and earth.
霄壤之别xiao rang zhi bie
as far apart as heaven and earth
霄壤之别xiāo rǎnɡ zhī bié
霄：云霄；壤：土壤，土地。形容差别很大。the difference between heaven and earth, a world of difference, poles apart