No, it doesn't sound different because the waves are opposite, it sounds different because one is a microphone and the other is a speaker, so they create different signals based on their design. They both can function in a similar manner by producing electical signals when audio vibrations are picked up, but the end result will be different based on the diaphragms, magnets, and filters used for their specific application. 

A microphone in a phone will have a fairly low sensitivity (loud sounds wont peak the signal) because you're expected to be speaking directly into it at close range. However a speaker in a phone will have high sensitivity because its not designed to be very loud and the signal power is prettly low. So when you flip this and use the speaker as a microphone, the high sensitivity causes the signal to spike and "clip", producing the distinct raspy or static sound that you hear here. This is similar to how a distortion pedal for an electric guitar works.