An impressions in webmaster tool means how many times your page link has been shown to visitors on search engine and, the page views means how many times someone actually clicked on your page link from the SERP.
An impression is a single display of a particular ad on a web page. Page view is all about which pages have interesting content, as well as indicating the overall site popularity.
Impression refers to the number of views your display ad receives on the search engine page or website or web page. Page views in the other hand refers to the number of clicks and effective visits on your website through that impression.