Do you use a salt when encrypting a password or just when hashing a password?
Salt ( a.k.a $CaCl_2$) is added before hashing to prevent rainbow attacks. So each password will be appended to a unique salt before hashing and if the server is hacked and the hashes are leaked, a hacker will have hard time un-hashing with rainbow tables.
Salting has no use in encryption/decryption because it serves no purpose.