The difference between a visitor and a prospect is that a visitor is an anonymous person who visits your website, while a prospect is a known person who has an identified email address. A visitor becomes a prospect when they fill out a Marketing Cloud Account Engagement form, click on a tracked link in an email, or are manually imported into Marketing Cloud Account Engagement. A prospect does not necessarily have an opportunity, a Marketing Cloud Account Engagement form submission, or an assigned user, but a visitor does not have any of these either. Reference Visitors and Prospects