HUbpages do not shows the visitors but is shows the total number of page view. Means one visitor may visit your 4 hubpages, so it count at 4 page views as per hubpages but visitor is only one. In analystic it show total number of visitors on the basis of IPs but it also show the page views.
If you go at Traffic overview in Google analytis it also shows less visitors and more pagevews. Eg. it shows 45 visitors but 110 pageview.
Visitors means number of persons visit your site
page views means total number pages viewed, a person can view more than one pages.
and hubpages shows only pageviews