PGP AFAIK is simply encrypting the content of an email with the public key of the person you're going to send it to. The address is public. PGP is a bit of a hassle in terms of exchanging public keys and integrating with legacy email clients/web clients.
Bitmessage has additional features, such as the ability to broadcast messages from a public address to all subscribers.
Especially with this client, Bitmessage is actually much more user friendly and powerful.
"PGP is a bit of a hassle in terms of exchanging public keys" this is true, but it's a bit of a necessary evil. How do you accomplish this in a secure and transparent way?
Bitmessage has additional features, such as the ability to broadcast messages from a public address to all subscribers.
Especially with this client, Bitmessage is actually much more user friendly and powerful.
To simplify,
PGP hides: content Bitmessage hides: content, recipient, sender.