At a glance
To understand the difference between Exit Rate and Bounce Rate for a particular page, keep the following points in mind:
For all pageviews to the page, Exit Rate is the percentage that were the last in the session.
For all sessions that start with the page, Bounce Rate is the percentage that were the only one of the session.
Bounce Rate for a page is based only on sessions that start with that page.
In depth
Let's clarify this last point with a simple example. Your site has pages A through C, and only one session per day exists, with the following pageview order:
Monday: Page A > Page B > Page C
Tuesday: Page B > Page A > Page C
Wednesday: Page A > exit
The Content report for Page A would show 3 pageviews and a 50% bounce rate. You might have guessed that the Bounce Rate would be 33%, but the Tuesday pageview granted to Page A is not considered in its Bounce Rate calculation. Consider that a bounce is the notion of a session with only one interaction from the user, and the session-centric analysis answers a simple yes/no question: "Did this session contain more than one pageview?" If the answer to that question is "no," then it's important to consider which page was involved in the bounce. If the answer is "yes," then it only matters that the initial page in the session lead to other pageviews. For that reason, bounce rate for a page is only meaningful when it initiates the session.
