Post-editing of machine-translation output is generally considered to be a distinct process from the revision of a human-translated text. The main reasons for this assumption are the quality of machine-translation output and the fact that it might be easier to criticize the work of a machine than the work of a fellow human translator. With the global shift of statistical machine-translation systems to neural machine-translation systems, however, the quality of machine-translation output has improved. What was true about differences between revision and post-editing in 2010 might therefore no longer be true today. In addition, translators hired to revise a text are not always aware of the origin of the text. This chapter compares revision and post-editing products made by professional translation agencies when the actual origin of a text corresponded to the instructions they were given (revision of a human translation, post-editing of machine translation) and when the origin did not match the instructions (post-editing of a human translation and revision of machine translation). We look at the number of edits made, the quality of the revision and the optimality of the intervention.