Empress (皇后; huáng hòu)
Only one in the imperial harem. The Empress had the highest status. The Empress was the principal wife of the Emperor. She had more power than any other concubines because she could have ten palace maids.
Imperial Noble Consort (皇貴妃; huáng guì fēi)
Only one such position in the imperial harem. Ranked only second to the Empress. The number of the palace maids she could have was eight. But the Emperor has been historically portrayed as sharing more love to her than to the Empress.
Noble Consort (貴妃; guì fēi)
Only two in the imperial harem. Each of them could have eight palace maids.
Consort (妃; fēi)
Only four in the imperial harem. They are respectively, Gui means noble, Xian means virtuous, Shu means kind & gentle, and De means moral. They could command a maximum of six palace maids.
Concubine (嬪; pín)
Only six in the imperial harem. They could have six palace maids.
Noble Ladies (貴人; guì rén)
Normally an unlimited number in the imperial harem. They can have a maximum of four palace maids.
First Female Attendant (常在; cháng zài)
Normally an unlimited number in the imperial harem. And they can have a maximum of three palace maids.
Second Class Female Attendant (答應; dā yìng)
Normally an unlimited number in the imperial harem. They can have a maximum of two palace maids.
Lady-in-waiting (官女子; guān nǘ zǐ)
Typically granted to female servants whom the emperor has taken to a liking and to accompany him without any official recognition. This rank was also not part of the official concubine ranking.
The Empress, Imperial Noble Consort, Noble Consorts, Consorts and Concubines can live in their own palace. Noble Ladies, First Female Attendants and Second Female Attendants all lived together.
* All the above information were derived from other online sources *