The distinction is that in one case, you are the new author, or co-author, so you are free to change the text itself. If you like timely more than opportune, or preferperspicacious over wise, then change away. It’s your document. But if it’s not your document, then suggest a word if you like, or simply comment that you think the author has made an odd or awkward word choice. Since it’s not your document, you don’t have to provide alternate language. Simply respond as the gentle reader to the clarity you experience with the text.
One might argue that where there is a clear violation of a grammar rule – maryland is spelled with a small-case m, or a plural subject is linked with a singular verb – useTrack Changes to fix the error. While this mechanically signals the need for a repair, it also involves a level of taking over that is best avoided. Simply comment to the problem.
Two quick examples of when the mechanical means can run afoul of the philosophical end:
1) As government contractors, we often deliver documents to our clients, which they approve, disapprove, or approve with comments. The delivered document is not approved for payment until the client and the contractor agree that it meets the requirements. What happens when a contractor gets back from the client a document loaded with changes created using Track Changes, pending contractor approval? At that point, whose document is it anyway?
2) In our writing critique group, we proof each other’s work electronically. In this case, the author is never contemplating the transfer of ownership of copyrighted work. So we use New Comment exclusively. Otherwise, by actually changing someone’s text, pending the author’s approval, haven’t I become at least a limited co-author?
When asking yourself which to use, remember the question is about the writing situation. Am I assuming ownership of a piece someone else started? Track Changes. Am I on a collaborative document project? Track Changes. Does someone else own this document before, during, and after I do my thing? New Comment.
Happy writing!