`ssh` keys and login-passwords are stored in separate locations on virtually any Unix-like system.  There's no reason why (aside from 30 years of history *preceding* `ssh`) the two couldn't have used the same storage.  But what we have now is separate, with scattered attempts to store the collection of credentials in key-managers.

Typically a user's `ssh` information is in **`$HOME/.ssh`**, while the logon information is in **`/etc/passwd`**, **`/etc/shadow`/**, **`/etc/group`** and **`/etc/gshadow`**.

A key manager ***could*** combine those, by providing passwords (or the analogous information) as needed.  But that's the exception rather than the rule.