I was chocked that I didn't knew the answer to this question immediately, offcourse we all know the result of putting someone in CC or BCC…

so here we go:

Cc
Cc is shorthand for Carbon copy . If you add a recipient's name to this box in an Outlook e-mail message, a copy of the message is sent to that recipient, and the recipient's name is visible to other recipients of the message.

Bcc
Bcc is shorthand for Blind carbon copy . If you add a recipient's name to this box in a mail message, a copy of the message is sent to that recipient, and the recipient's name is not visible to other recipients of the message. If the Bcc box isn't visible when you create a new message, you can add it.