Bouncing refers to instances where we render a track to audio within the session in Ableton. Exporting refers to bouncing a track to audio and saving it outside of the DAW (say, on your hard drive somewhere). Exporting can be used to save samples that we like and may wish to use again. However, exporting typically refers to the process of rendering an entire project (e.g., song) as an audio file, called a mixdown.