All public books are moderated, during which time social sharing and embeds are turned off and the books don't appear on your profile, in search, or in the feeds of your followers. Once approved, the book appears everywhere.
Private books can be shared via email and your private book link. Private books do NOT appear on your profile, in search, the feeds of your followers and can't be embedded or shared using the social network tools.
Also, you can speed up moderation of your public books by upgrading to Membership. Membership includes "Accelerated Moderation", which puts your books in a separate, faster queue that's reviewed before other stories.