Bounce rate uses the Bounces metric and is calculated as:
Bounces divided by Entries
Bounces are a visit that consists of a single server call. For example, a single page visit is a bounce if a visitor does not interact with the page in a way that sends data to Adobe, such as clicking a link or a video start. If more than a single hit is received in a visit, a Bounce is not counted.
Entries represents the number of times a given value is captured as the first value in a visit. Entries can occur only once per visit. However, it is not necessarily the first hit if the variable is not defined.
Bounce Rate does not include visits where multiple actions occurred on a single page. For example, a visit with a video view on a single page is a Single Access but not a Bounce.
Exits - The number of times a given value is captured as the last value in a visit. Exits can occur only once per visit.
In your case it make sense that page flow exit (not a bounce) rate should not match with bounce rate, as both are not being derived by same formula.
Thanks!
Asheesh