If the password is a word that may well be enriched with digits, such as "rainer003", then the passphrase is a letter- digit-character combination that is generated by a random generator and communicated to the user.
A passphrase is a longer string of characters consisting of uppercase and lowercase letters, digits, special characters, and spaces, and is case-sensitive. Since the string has no relation to the user and is randomly composed of different characters, it is relatively difficult for the user to remember such a character combination. Example: "ok4J67_Bm654".
The advantage of the passphrase over the password is that a password often has a direct relation to the user and his circle of persons and can thus be determined by repeated trial and error. The situation is different with a passphrase, which, if it consists of only eight letters and digits, already forms a 36! to 8! (factorial) and thus forms a much higher security. This is tens of millions of possibilities. If only upper and lower case letters are used, it is already a 52! to an 8! This results in over 750 million different combinations.
Passphrases are used for logging in, in encryption, signatures, and for access blocks.