What is the difference between mcrypt and scrypt?

Mcrypt is a simple crypting program, a replacement for the old unix crypt . When encrypting or decrypting a file, a new file is created with the extension .nc and mode 0600. The new file keeps the modification date of the original. The original file may be deleted by specifying the -u parameter. If no files are specified, the standard input is encrypted to the standard output.

Mcrypt uses all the symmetric algorithms included in libmcrypt.^{Man Page}

Scrypt is a password-based key derivation function created by Colin Percival. The algorithm was specifically designed to make it costly to perform large scale custom hardware attacks by requiring large amounts of memory, and is designed to be far more secure against hardware brute-force attacks. In 2012, the scrypt algorithm was published by IETF as an Internet Draft, intended to become an informational RFC, which has since expired.^Tarsnap