Difference Between Monoalphabetic Cipher and Polyalphabetic Cipher

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Monoalphabetic Cipher	Polyalphabetic cipher
Once a key is chosen, each alphabetic character of plaintext is mapped onto a unique alphabetic character of a ciphertext.	Each alphabetic character of plaintext can be mapped onto “m” alphabetic characters of a ciphertext.
The relationship between a character in the plaintext and the characters in the ciphertext is one-to-one.	The relationship between a character in the plaintext and the characters in the ciphertext is one-to-many.
A stream cipher is a monoalphabetic cipher if the value of ki does not depend on the position of the plaintext character in the plaintext stream	A stream cipher is a polyalphabetic cipher if the value of id does depend on the position of the plaintext character in the plaintext stream.
Monoalphabetic cipher includes additive, multiplicative, affine, and monoalphabetic substitution cipher.	Polyalphabetic cipher includes autokey, Playfair, Vigenere, Hill, one-time pad, rotor, and Enigma cipher.

A polyalphabetic cipher is any cipher based on substitution, using multiple substitution alphabets. The Vigenère cipher is the best-known example of a polyalphabetic cipher.
The Enigma machine is more complex but is still fundamentally a polyalphabetic substitution cipher.

A Monoalphabetic cipher is any cipher in which the letters of the plaintext are mapped to ciphertext letters based on a single alphabet key.
Substitution ciphers work by replacing each letter of the plaintext with another letter. For this reason, a monoalphabetic cipher is also called a simple substitution cipher.