Difference between debug, release builds

[YaronAlexandrovich]

There are four scenarios:

Run a debug session using the 'PE Debug' build

Run a board that has been flashed with a 'PE Debug' build, not in debugger

Run a debug session using the 'PE Release' build  

Run a board that has been flashed with a 'PE Release' build, not in debugger

I know RTFM is the right answer here, but I would appreciate a brief explanation of what is occurring in each of these 4 scenarios, as each leads to different behaviors.  
Also, to prove code correctness, I assume the code should work properly under a 'PE Release' non-debug session.  As of now only a 'PE Debug' debug session works correctly.  

[Alice_Yang · Accepted solution]

Hello @YaronAlexandrovich 

Do you mean MCUXpresso IDE? If yes, please see <MCUXpresso_IDE_User_Guide.pdf>

MCUXpresso IDE creates projects with two build configurations, Debug and Release (but you can also add more if required). These differ in the default level of compiler optimization.
Debug projects default to None (-O0), and Release projects default to (-Os). For more information
on switching between build configurations, see How do I switch between Debug and Release
builds? 

BR

Alice