Why 1984 — partly for social reasons, the American text changed ‘thick negroid’ (page 80, lines 9-10) to ‘protuberant’.

Seeker & Warburg in England and Harcourt, Brace in the USA both felt the need to press ahead urgently with publication. Instead of waiting for the page proofs of the English edition from which to set the American text, Robert Giroux in New York went ahead and prepared copy for the American printer independently of Roger Senhouse's copy-preparation for the English printer. The result is two different texts, partly because American conventions dictated a completely different system of punctuation and because Americans were accustomed to different verbal usages — Orwell's use of ‘towards’ was changed throughout to ‘toward’, for example — and partly for social reasons: for instance, the American text changed ‘thick negroid’ (page 80, lines 9-10) to ‘protuberant’. In addition, Orwell, as he had when preparing the Gollancz edition of Burmese Days, seems to have made a few verbal changes when checking the American proofs. The. most interesting of these is the avoidance of the repetition of ‘job’ on page 50, lines 22 and 23, where ‘version’ was substituted for its second appearance.

George Orwell: ‘Nineteen Eighty-Four’. Peter Davison: A Note on the Text

https://orwell.ru/library/novels/1984/english/eint_pd