All my passwords look like @A#vVukh9c$3Kw4Cs8NP9xgazEuJ3JWE and are unique.
You're still transmitting the actual secret to the destination, so interception is a risk. Passkeys use asymmetric cryptography: no reusable secret is ever transmitted, only time-sensitive challenges that prove possession of the private key. Servers only store public keys, which aren't secret by design.
Passkeys have multifactor authentication built-in whereas passwords do not.
Passkeys can be more convenient than passwords. My password manager has my passkeys. At login, my password manager raises a passkey prompt that I simply confirm.