What the difference between "Passphrase", "Passcode" and "Password"?
Is a passphrase a multi-word phrase? And a passcode a simple password?
Wikipedia explains "Passphrase", "Passcode" and "Password" reasonable well. In general, passphrases are long passwords and passcodes are numeric-only passwords.
This is all really just playing with terminology. Any of the three describe a component of an authentication system: Something you know (that, hopefully, no one else does).
A "passphrase" commonly accepted to mean a long string used for a password-- a "phrase" ("The only thing we have to fear is fear itself.", "What's that blue thing doing here?", etc). Generally these are used for things like unlocking private keys, or password "vaults" that contain other passwords. A pass-phrase has more entropy than a password, typically, because a passphrase has more bits of randomness in it. Depending on what kind of software you use you may never use a passphrase.
A password is typically a short string of characters. You use them every day, and you know what they are.
A passcode? I dunno... I don't think there's any commonly accepted definition.
Password is just that, a word. Passcode, however, can have a word in it, but word or not, it'll contain numbers and symbols. For example, P@sSc0d3 or 57:$8&%$94.