Exit rate as a term used in web site traffic is the percentage of visitors to a site who actively click away to a different site from a specific page, after possibly having visited any other pages on the site. The visitors just exited on that specific page.
Bounce rate is the percentage of single page visits or web sessions, It is the number of visits in which a person leaves your website from the landing page without browsing any further. Google analytics calculates and reports the bounce rate of a web page and bounce rate of a website.