PBKDF2 (Password-Based Key Derivation Function 2) is a key derivation function that is part of RSA Laboratories' Public-Key Cryptography Standards (PKCS) series.
SCrypt is a key derivation function (KDF) based on the concept of sequential memory-hard functions mostly used for password hashing.
|Better option bcrypt||
"Pbkdf2 is arguably a better option than bcrypt scrypt having been much more thoroughly studied and tested"
from question "Password Security for Shared Hosts (PHP 5.2+)"
"Bcrypt is weaker than scrypt although still three orders of magnitude stronger than pbkdf2 because it only requires 4 kb of memory"
from question "What are optimal scrypt work factors?"