Mnemonic phrase (mnemonic seed/mnemonic recovery phrase/mnemonic seed) is a sort of 2FA (two-factor authentication) for your crypto wallet. It is a list of 12, 18 or 24 words which store all the information needed to recover your wallet. This mnemonic phrase is human readable, and it’s used by almost all well-regarded wallets. Mnemonic phrases are generated automatically via BIP-39 specification standard.
Mnemonic passphrase is an additional security layer, simply put, a password for your mnemonic phrase. It consists of 13 to 25 words, and you have to be pretty careful with it, because if you lose it, it will be hard to gain your funds back.