A Page View represents each time a user visits a page. This means that a single user loading the same page 5 times in a single session will generate 5 page views.
Unique Page Views represent a total of page views generated by a user during the same session. This means that if the same user loads a page 5 times in a given session, it's only calculated as 1 unique page view. This is why page views will always outnumber unique page views.