be as far apart (/as different) as heaven and earth; a world of difference ? 比起先前用皂莢時(shí)候的只有一層極薄的白沫來，那高低真有～。(《魯迅選集》上—128) The difference between these and the small white bubbles produced by honey locust pods was like that between heaven and earth.
霄壤之別xiao rang zhi bie
as far apart as heaven and earth
霄壤之別xiāo rǎnɡ zhī bié
霄：云霄；壤：土壤，土地。形容差別很大。the difference between heaven and earth, a world of difference, poles apart