in Editing
Beta readers and editors do different jobs
Beta readers tell you how a book feels to read. Editors tell you why, and what might be done about it. You may want both.
Many writers show their work to beta readers before sending it to an editor, or instead of sending it to one. Beta readers are people who read a draft and report back on their experience. Editors are professionals who assess a manuscript and advise on it. Both are valuable. They are not substitutes for each other, and knowing what each can offer helps you use both well.
What beta readers offer
A beta reader's great strength is that they read as readers. They are not looking at the craft. They are experiencing the story, and they can tell you where they were gripped, where they were bored, where they were confused, which characters they liked and whether the ending satisfied them.
This is information that no one else can give you, and it is often more reliable than a writer's own sense of the book. Several beta readers independently putting a book down at the same chapter is a strong signal.
Beta readers from within a book's intended readership are especially useful, since they bring the expectations of genre and audience that the book will eventually meet. Beta readers with relevant lived experience can also point out where a portrayal does not ring true.
What beta readers usually cannot offer
Most beta readers can tell you that something is not working. Fewer can tell you why. A reader may say the middle dragged, without being able to identify that the cause is a subplot that does not raise the stakes, or a run of scenes with the same emotional shape.
Beta readers also tend to suggest solutions based on their personal preferences. "I wish she'd ended up with the other one" is useful as a reaction but not necessarily as advice.
They will also vary widely in how carefully they read, how candidly they report and how much they know about the genre. Friends and family, in particular, may be kind rather than frank.
What editors offer
An editor diagnoses. They read with an understanding of how books are built, and they can usually identify the mechanism behind a reader's reaction. They can explain why the middle drags and suggest several ways to address it. They can also spot problems readers might not consciously notice, such as point-of-view slips, pacing patterns or structural imbalances.
An editor also reads with the whole manuscript in view and in relation to what similar books do. That broader context is part of what a professional brings.
Using both
A common and sensible sequence is to use beta readers first, revise based on consistent feedback, and then bring in an editor. This means the editor sees a stronger draft and can focus on problems the writer could not solve alone.
Some writers do the reverse, using an editor for structural work and beta readers afterwards to test whether the revisions land. That can also work.
When reading beta feedback, look for patterns rather than individual comments. When reading editorial feedback, pay attention to the diagnosis even if you prefer a different fix.
Both are forms of the same thing: finding out how the book reads to someone who is not you.