An orthodontist is a qualified dentist who has chosen to specialise in this area of dentistry by completing a further three years of postgraduate university-based training. An orthodontist focuses mainly on correcting the position of your teeth and jaw, rather than day-to-day maintenance such as fillings, crowns and wisdom teeth removal.
Just as there are specialists in medicine (such as cardiologists, gastroenterologists, neurologists, etc.), there are specialists in dentistry. Just like you’re best to get a cardiologist to perform your heart surgery, you’re also best to choose an orthodontist for your orthodontic treatment.