Difference: Digital signature is encrypted with the sender's private key, and the receiver uses the sender's public key. This is a one-to-many relationship, and anyone with the sender's public key can verify the correctness of the digital signature.

Digital envelopes are encrypted with the public key of the receiver, which is a one-to-many relationship. Anyone who owns the receiver's public key can send an encrypted message to the receiver, and only the only person who owns the receiver's private key can decrypt the message.