What are the most significant differences between how a Linux bridge and an Open vSwitch work?
Open vSwitch has a section on that in their FAQ:
Q: Why would I use Open vSwitch instead of the Linux bridge?
A: Open vSwitch is specially designed to make it easier to manage VM network configuration and monitor state spread across many physical hosts in dynamic virtualized environments. Please see
[WHY-OVS.md] for a more detailed description of how Open vSwitch
relates to the Linux Bridge
The entire list of features/differences (WHY-OVS.md) is quite long, you should check it out if you want to know all the details. The short version is that Open vSwitch is targeted at large multi-server virualisation environments, so it is focused on logical abstraction and management; the Linux bridge is fast and reliable, but lacks all fancy control features.