Effects of switching from /SUBSYSTEM:CONSOLE to /SUBSYSTEM:WINDOWS

What are the effects of switching from /SUBSYSTEM:CONSOLE to /SUBSYSTEM:WINDOWS? I have noticed my application (a qt GUI application) now doesn't work correctly in开发者_如何学编程 release mode. If I put the console back in it works fine. I have tried getting rid of any prints to console but I am still seeing issues. The program links to a .dll library that was originally a console application but became a dll later on, it has also had its subsystem changed to WINDOWS. Only when they are both on CONSOLE and a console is present does it work correctly/stably.