It’s common for newer developmental editors to focus on critiquing rather than editing an author’s work. Developmental editing (also called story editing or content editing) does contain elements of critique but it is more than that.
To do a good developmental edit, I have to immerse myself in the story world, to try to understand what it is and what it’s trying to be. I’m not just saying, “I was confused here.” That is critique, not editing. A lot of developmental editors say that what they do is development when it is actually critique.
In a developmental edit, what I am trying to do is guide an author in understanding what strategies will help them make their story more closely match what they want it to be, whether this is an ideal in their head, the conventions of a particular genre, or the commercial elements that will help them get an agent.
This is complex undertaking and is far more than the reader reaction that some editors make it out to be. While reader reaction is immensely valuable for the writer seeking it as well as for an aspiring editor trying to hone their skills (that’s why I’ve started the Beta Reads + Critique Partners forum), it is not developmental editing.
It is important as a developmental editor to work on building your understanding of storytelling strategies and techniques and how they can be used to produce various results. It is equally important to be able to understand when and how storytelling strategies and techniques are causing story problems or are being inexpertly deployed by the author.