An editor improves the manuscript. A beta reader tells you how it feels to read. Those are different questions, and a book usually needs both. Understanding the difference helps you use each at the right moment and avoid asking one to do the other's job.
A reader, not a fixer
A beta reader reads your book the way a reader would: for the story or the ideas, not to find typos. They tell you where they got lost, where they lost interest, which character they did not believe, and which part they could not put down.
That is something an editor, who reads closely and professionally, cannot fully reproduce. By the time an editor has worked on a book, they are inside it. A beta reader meets it fresh.
What an editor does that a beta reader does not
An editor has the training to diagnose why something is not working and to suggest how to fix it: restructuring a plot, tightening an argument, correcting grammar and consistency. A beta reader is usually not expected to do any of that.
A beta reader says that something feels slow. An editor can tell you why and what to cut.
When to use a beta reader
The usual moment is after you have revised the draft yourself and before you pay for a professional edit. Feedback from real readers can show whether the story works at all, which changes what kind of edit you need and may save you from editing material you will later rewrite.
Beta reading also suits the stage before a launch if you want to know how your target readers react.
What to ask them
Open feedback such as "What did you think?" is fine, but specific questions give you more to use.
- Where did you want to stop reading, and why?
- Was anything confusing, or did you have to reread something?
- Which characters did you care about, and which did you not?
- Did the ending feel earned?
- Would you recommend it, and to whom?
- What would you tell a friend it was about?
How to use what you hear
One reader's reaction is an opinion. The same reaction from several readers is a pattern. Look for the points that come up more than once, and be cautious about fixing something only one person mentioned.
You do not have to agree with everything. The aim is to see your book through someone else's eyes, then decide what to change. Marlowe's beta reading service gives you a structured report you can act on.