Richard Straub wrote an amazing article entitled "The Concept of Control in Teacher Response: Defining the Varieties of `Directive' and `Facilitative' Commentary" that explains these two types of commentary very well with examples. Below are reflections of both types of commentary that we as Writing Fellows-in-training have written.
Christine: "I instructed the writer of the LeMoult paper way to often. My style was too directive. I wrote a lot of `Don't do this' or `Don't use this word..' or `This isn't a good way to start your paper..' which is so dangerous. Even though the writer needs tons of help I should pick and choose my battles. I realize [that I] did use some shorthand that could be very mysterious, such as `awk'" (Newsgroup 9/22/97)
Stacey: "I am not so happy about how some of my comments resembled Peterson's reactions. For example, I wrote `Citation?'. Looking back, I think that kind of commentary, in large quantities, demonstrates too much attitude." (Newsgroup 9/21/97)
Myself: (about my first commentary) "In many ways I am controlling. I have a personality that is very type A and I saw in my need to help (and my belief that I 'knew best') my commenting style fell between White's and Peterson's. Many of my comment were inflexible statements, e.g. `This is summary, respond to the ideas, do not just restate them'." (Newsgroup 9/21/97)
Nancy: "My suggestions seem directive, not so much in a harsh, `do-it-my-way-or-else' manner, but I think I attempted to assert my authority over the student by creating many of my comments as corrections." (Newsgroup 9/19/97)
Nancy: "I would try to make my comments more facilitative. I would not correct every grammar mistake, and I would try to act more like a friend who is merely reading the essay and providing feedback and reaction" (Newsgroup 9/19/97)
Christine: "I suppose the best way to handle commentary is well-worded, not terse questions, lik[e] Gene used in her commentary." (Newsgroup 9/22/97)
Laurie: "When I wrote the LeMoult commentary, I did include a lot of questions for the writer to consider." (Newsgroup 9/21/97)