How do dental hygienist and orthodontist differ?

Dramatically: Hygienists are relegated to cleaning teeth and monitoring periodontal health while orthodontists are dentists who have specialized to move teeth and correct occlusions.

Very different: Hygienists clean teeth. Orthodontists straighten teeth and correct misaligned bites. Career wise, an orthodontist requires about 5 more years of training than a hygienist, but also typically makes a much more substantial income. One is a doctor, the other is not.

Very Different: Orthodontists are dental specialists who specialize in tooth movement. A dental hygienist is not a dentist. He/she is someone who trained in hygiene school to clean teeth under the direction of a dentist.

Very different: A Dental Hygienist has 2 years full time training after high school in cleaning your teeth, teaching you proper Oral Hygiene techniques, and doing a pathology survey. An Orthodontist is a Dental Specialist with 4 years of College, 4 years of Dental School, and 2-5 years of a full-time Orthodontic Residency, and who limits his practice to resolving malocclusions (dento-facial growth & development)