Qmake having different define preprocessor words per config

[toglia3d]

I started using qmake yesterday, and it was pretty easy. I could understand and do almost everything I needed.

Now, normally in my eclipse projects I use two of my own preprocessor keywords to exclude "asserts" when doing a release build, and those are DEBUG and RELEASE.

What bring me here is that I noticed I could do both builds by using "debug_and_release" on my "CONFIG", in that case how would I specify my different preprocessor defines for each build an a same .pro?

Is it meant to have two .pro? in that case why is building debug and release in conjunction an option.

Are there already any preprocessor keywords to differentiate if its a debug or a release build?
Edit: SOLVED QT_DEBUG and QT_NO_DEBUG