Is scrypt a hashing function, encryption, or PBKDF?
Scrypt is most certainly a password-based-key-derivation-function.  So is PBKDF2, although it can be confusing since PBKDF2 is an eponym.  To add to the confusion, Scrypt uses PBKDF2 internally (which may be the hashing function you refer to), as well as the Salsa20/8 Core function (which may be the encryption function you refer to).  Further reading here.