I have to thank a friend of mine for doing all the testing on this, but many times I’ve starred at the “Should Configuration Manager enforce specific behavior regardless of the application’s intended behavior?” options along with the Return Codes tab.
Reboot options on the “User Experience” for a Deployment Type
Return Codes and application intended behavior
Below is what happens when selecting the four different options in the drop down, assuming a 3010 return code from the application.
No specific action.
Software Center “Restart required” text: No
3010 causes reboot? No
3010 System Center “Status” text: Installed
Whether or not the software is Required or Available, the computer is not forcibly restarted and no reboot prompts are displayed.
Determine behavior based on return codes:
Software Center “Restart required” text: Might be required
Application return code: 3010
If the installation is Required then following dialog is displayed.
If the software is Available then the computer is not forcibly rebooted and no countdown timer is displayed, only an optional reminder which the user can cancel.
Below is the text displayed in the Software Center when the application gives a return code of 0. 
The software install program might for a device restart:
Software Center “Restart required” text: Might be required
3010 causes reboot? No
3010 System Center “Status” text: Installed
If the application installation does cause a reboot it is not logged as an error condition within the Software Center.
Whether or not the software is Required or Available, the computer is not forcibly restarted and no reboot prompts are displayed. This setting is used to ensure that if the application installer itself (e.g. setup.exe) performs a reboot of the system, the SCCM agent is able to handle this scenario and doesn’t consider it to be failure.
Configuration Manager client will force a mandatory device restart:
Same behavior as Determine behavior based on return codes however it is not based on the return code of the application package.