Hi

When you record in mono, the signal will be sent to the left and right channel. It's exactly the same signal. When you record in stereo, there will a diffference between left and right (AB, MS, ORTF for exemple).

Just listen the difference between a sound recorded with one mic and one AB couple.

close one ear and listen to a sound - that's mono. With both ears - stereo. Stereo microphone pairs try to recreate what you hear when both of your ears are open (unless you're intentionally positioning the microphones in an original way)

interesting.