The difference between views and clicks is related to the level of engagement with your assets a visitor has shown.
By definition:
Views are the total number of times visitors have been exposed to your assets, such as newsletter promotions, mailshots, banners or Technology Center pages.
Clicks are the total number of times visitors have clicked on your assets after seeing them.
In summary, the difference between views and clicks is that a click is a step further that a visitor takes after being exposed to any of your assets.