Editing and proofreading are two different stages of the revision process, even though customers and agencies alike often confuse them or use the terms interchangeably!
Editing is undertaken with the aim of improving the flow and quality of writing, concentrating more on the terminology than on the form. Editors need to check for contextual inconsistencies and verify the facts to make sure the correct terms were used. In order to do the job well, editors often should research using specialised dictionaries and glossaries from the field concerned, as well as websites and other useful resources. They also recommend what corrections should be made, and sometimes rewrite whole paragraphs if necessary, or change the style of the translation. However, it is usually the original translator who makes the final call after reading the editor's suggestions.
Proofreading is the final stage of the revision process. It involves checking a translated document against the original and making sure everything is correct. The proofreader should look for spelling, grammar, syntax and punctuation mistakes, as well as typos. The proofreader may make suggestions and comments as well, also referring to the context, and ask questions before returning the document to the editor.
I provide both editing and proofreading services to my customers, either separately or as part of my translation service, if desired – please contact me for rates.