Monaural: Sound perception through one ear. In relation to headsets, a one-eared listening device. Monaural headsets have far less noise cancellation technology than binaural headsets but are lighter and less invasive, allowing for longer wearing time. Monaural headsets are great for environments in which one needs to be aware of their surroundings and others.
Binaural: Sound perception through both ears. In relation to headsets, a two-eared listening device. Binaural headsets have much more noise cancellation technology than monaural headsets and are very effective in noisy, distracting environments. They are great for environments in which one does not need to be immediately aware of their surroundings and can full focus on the task at hand.