Total Visitors refers to the number of unique visits to a site. That could be different people, different devices, or different IP addresses. So if 1 person looks at a site from their phone and their laptop they've register as 2 visitors since there's no way for us to know those two separate devices were used by the same person.

Total Views refers to the total number of times a site was opened and viewed. So if that same person viewed the site 6 times from their laptop and twice from their phone, you would get 2 visitors and 8 visits.