Difference between debug and release apks

Question

I am new to android as well as android studio. From my experience in visual studio, when we test the .exe in another machine we copy the release folder and .exe.

But

Answer 1

One important difference is that release APKs typically have had ProGuard (code shrinking) run on them, which detects and removes unused code to reduce the APK size.

From Shrink Your Code and Resources:

Be aware that code shrinking slows down the build time, so you should avoid using it on your debug build if possible. However, it's important that you do enable code shrinking on your final APK used for testing, because it might introduce bugs if you do not sufficiently customize which code to keep.

Your colleagues are probably testing on the debug build type to save time, because it can take significantly longer to build the release APK as opposed to the debug APK.