In an openssh-server login to a GNU/Linux machine

to use a private ssh key encrypted with an N-characters passphrase, then `sshd_config`:
```
PasswordAuthentication no
PubkeyAuthentication yes
```

is it equivalent to use a login with a password that is always N-characters long?
```
PasswordAuthentication yes
PubkeyAuthentication no
```

in the event of a bruteforce attack.