The difference from IP-based identification is the unit of answer. IP-based tools say "someone from this company visited". Person-level tools say which person, what they read, and how to reach them.
That changes the next step from research to outreach. You are not looking for a person at a company; you have the person.
Visitor InSites is a person-level tool: in its own words, it turns "anonymous site traffic into named contacts with email, phone, and LinkedIn. B2B and B2C." It is the company behind Buzzlist. Once you have the name, Buzzlist writes the four emails to that person from their company website.
