Does a pass phrase uniquely identify public and private keys?

[Bitcoin]

Does a pass phrase uniquely identify public and private keys?

If I go to bitaddress.org and create a paper wallet with BIP38 and a pass phrase, what it doing with that pass phrase specifically? Since it can make multiple paper wallets from one pass phrase, the phrase must not uniquely identify the public and private keys.  But if it does not, what use is the phrase?

Source: Does a pass phrase uniquely identify public and private keys?