In-ear Bluetooth earpieces are good for taking work calls on the move, as we’ve already mentioned. They’re cheap, simple and tend to work best with a smartphone, but they won’t block out outside noise and offer little in the way of long-term comfort or extra features.
Monoaural headsets (or Britney headsets, colloquially) are the sort you might see a telemarketer, call center agent or legendary pop singer wearing. As they only have one earpiece, they're a good compromise if you don't have to completely block out the outside world at work. They often offer similar features to traditional headsets at a reduced cost, making them great value.
Binaural headsets are your traditional on-ear or over-ear headphones. Technically, any pair of headphones or gaming headset you might own counts as binaural. They’re the only variety to offer full active noise cancellation (ANC) and the only variety suitable for listening to music; they also tend to be the most expensive, but compensate with plenty of features and supreme comfort.