Short answer: no difference. They mean the same thing.
Someone goes into a business as a normal customer, pays attention to what happens, and writes it up afterward. Some people call that a secret shopper. Some call it a mystery shopper. It's the same job either way.
Why two names exist
No real reason. It's just what stuck for whoever was talking about it.
Some companies use secret shopper because that's what their industry has always called it. Others use mystery shopper because it sounds a little less like spying and a little more like a review. Some regions lean one way, some lean the other. None of it changes what actually happens during the visit.
If you're searching for this online, use whichever term you like. You'll find the same kind of company either way.
A few terms that actually are different
Most of the industry's vocabulary is just this one idea said different ways. But a couple of terms mean something else, and mixing them up can get you the wrong service.
Compliance audit. This checks whether a business is following specific rules. Was ID checked before serving alcohol. Was a safety procedure followed. It's not about how friendly the staff was. It's about whether a rule was followed, yes or no.
Phone shop. This is a call, not a visit. Someone rings the business and evaluates how the call went. No one walks in.
Online or web shop. Someone tests a website or app instead of a physical location. Checking out, browsing, live chat, that kind of thing.
If a company only offers one of these, it might not be what you're picturing when you think of a mystery shop. Worth asking exactly what's included before you book anything.
Common questions
Is a secret shopper the same as a mystery shopper?
Yes. Same job, same idea. A real person visits a business as a normal customer, then reports back on what happened. Different people just picked different words for it.
Why do some businesses say secret shopper and others say mystery shopper?
Mostly habit, region, or which term a company picked when they started. Neither one is more official or more professional than the other.
Are there terms in this industry that do mean something different?
Yes. A compliance audit checks whether rules are being followed, not the customer experience. A phone shop only covers a call, not an in-person visit. Those are worth knowing apart, even though secret shopper and mystery shopper are not.
What actually matters
The name doesn't matter much. What matters is what you get afterward.
Ask what the report actually covers. Ask if you can see a sample before you pay. Ask whether it's a one-time visit or something you can repeat. Those questions tell you more than whether the company calls itself secret or mystery.
We use mystery shopper, mostly because it's in our name. Same service either way.