The proofreader and the copy-editor are in charge of making sure that the text of any product that involves writing (such as magazines, newspapers and books) is free of any errors, whilst ensuring that texts are engaging and accessible to the readers.
Proofreading involves correcting grammatical and spelling errors, while copy-reading involves looking at the work and fixing any problems with style and tone.
Copy-editors usually do fact-checks as well, making sure that everything in the text is accurate and true. Most publications combine both job roles into one position (in which case, they’re called copy-editors rather than proofreaders).
Copy-editors are usually hired by newspapers. Some magazines have copy-editors and proofreaders, too, but their longer production time allows for the use of fewer people to assess the articles. In book publishing, the proofreaders also do some administrative work, such as coordinating with writers and with printers.