SciPHRPasskeys vs seed phrases.
Both protect an account with a key. The difference is whether the key can be typed somewhere it should not be. A seed phrase can. A passkey cannot. That one property decides whether a convincing fake interface can take the account.
A secret you can type anywhere.
A seed phrase is a list of words that encodes the key. Because it is text, it can be entered into any app or site. A password has the same weakness, which is exactly why a convincing fake site can steal it. The seed phrase only has to be typed into the wrong place once.
A key bound to the real site.
A passkey is cryptographically bound to the real site or app it was registered for. It lives on your device and is released only behind a biometric. When a lookalike phishing site asks, the browser or operating system sees a different origin and the passkey simply does not apply. The fake one never even gets the option to ask.
The core difference
A password or seed phrase can be typed into anything, which is why a convincing fake can capture it. A passkey is bound to the real site it was registered for, so the fake one never gets the chance. The protection moves from human caution to a property of the key itself.
Recovery has to keep the property.
A passkey removes the phishing moment, but losing a device still has to be handled. The point is to provide recovery that does not quietly reintroduce a single typed secret. If the backup path is itself a phrase a person can enter anywhere, the anti-phishing benefit is undone. Good designs keep the key on the device and enforce recovery through factors that cannot simply be typed into a fake screen.
Related: what is a seed phrase, what is a private key, what is self-custody.
Common questions.
What is the difference between a passkey and a seed phrase?
A seed phrase is a secret you can type into anything, so a fake interface can capture it. A passkey is bound to the real site or app it was registered for, held on your device, so the fake one is never offered the chance to ask.
Why can a passkey not be phished?
It is tied to the specific origin it was created for. The browser or OS only uses it on that exact site or app. A lookalike has a different origin, so the passkey does not apply there.
Is a passkey the same as not having a key at all?
No. There is still a private key. It just stays on your device and is released behind a biometric, instead of being shown to you as words you could be tricked into entering elsewhere.
Does using a passkey mean I cannot lose access?
No. Recovery still matters. Good designs back up the key securely and avoid reintroducing a single typed secret, so you keep the anti-phishing property while still being able to regain access.