Your Page Title shows at the top of the page, and is also the first line that shows up when your page comes up in a Google search result. Make sure each web page on your site has a unique Page Title that relates to what the page is about.
Your Page Description show up under your url in a Google search result and tells people what exactly each page on your site is about. Page Descriptions should be unique on every page and no longer than 130-155 characters.