Although the terms nutritionist and dietitian are not protected in Australia, all nutrition professionals who have had a substantial amount of training in nutritional science (and therapeutics) should also be registered with the appropriate body.  Registered Nutritionists and Dietitians alike must maintain their knowledge through regular continued professional development and  be insured Furthermore they are bound strict ethical guidelines and codes of conduct.

So what kind of nutritional professionals will you find  here in Australia?

You will find:-

Dieticians Help people who are already sick, modify diet to improve medical conditions,
Nutritionists help people remain healthy through nutritional advice.
Associate Nutritionists and Registered Nutritionist – are registered  with the Nutrition Society of Australia Voluntary Register of Nutritionists,where as dieticians are registered through the Dietetians Association Australia,
Each governing body has different regulations and requirements for registration. Additionally, most award various acolades and post nominals depending how experienced you are in your field.
Associate Nutritionist (A.Nutr)
Qualification: At least a degree in nutrition, registration accepted following peer assessment by reputable registered nutritionists of  Nutrition Society of Australia/ Voluntary Register of Nutritionists
Where do they work: Associate nutritionists are normally recent nutrition graduates who have yet to obtain enough work experience to gain full registration.  Associate Nutritionists will have enough nutritional background to give sound dietary advice and guidance and depending on their degree, have experience in public health, sports nutrition and/or nutritional therapeutics.
If not providing nutritional advice, Associate nutritionists may be studying for higher research degrees, working for food or pharmaceutical companies or even in the media
Registered Nutritionist (R.Nutr)
Qualification A minimum of a degree in nutrition plus at least 3 years experience and/or 3 years post-graduate qualification (MSc plus experience or PhD)
Registration Body: Nutrition Society of Australia – Voluntary Register of Nutritionists
Where do they work: Registered Nutritionists work in a variety of roles, public health, nutritional/food, research, sports nutrition, private nutritional practice or academia.
Accredited Nutritionist (AN)
Registration Body: Dietitians Association for Nutrition (DAA)
Qualifications: Postgraduate qualifications in nutrition and five years experience (NB the DAA discriminates against overseas professionals working in Australia from holding these credentials).
Where do they work: These nutrition professionals that have the expertise to provide a range of nutrition services including tertiary education services related to nutrition, public health nutrition and community health, but excluding individual dietary counselling, medical nutrition therapy and group dietary therapy  so you can’t get your nutritional advice here!
Registered Dietitians (RD) and Accredited Practicing Dietitians (APD)
Registration Body: Dietitians Association for Australia (DAA)
Qualifications: Degree in dietetics (and nutrition)- this will include a year of clinical practice or a postgraduate qualification in dietetics.
Where do they work: Registered dietitians and Accreditied Practicing Dietitians work treating people who are ill, using diet to manage or alleviate symptoms. This can be  in hospitals, in the community in collaboration with a GP (as part of a care plan) or in private practice. Registered Dietitians are normally newly qualified dietitians (or have recently registered with DAA with overseas qualifications) , for the credentials of Accredited Practicing Dietitian APD , RD registered dietitians must undergo a period of supervised clinical practice with an APD.
Naturopathic Nutritionists Registration Body: Various
Qualifications: Advanced diploma in nutritional medicine (TAFE award) or a degree in naturopathy with a major in nutrition
Where do they workNormally in private practice.  These nutrition practitioners often use alternative methods of diagnosis and therapy which may not be scientifically verified.  Although the methods are not scientifically proven, many people still prefer to seek nutritional advice from alternative therapists
Who else calls themselves nutritionists.
Well, the truth is anyone can call themselves a nutritionist! Ultimately, it is important that you chose a nutrition practitioner who has appropriate qualifications, insurance and registration with a professional body.  If you are unsure if your nutrition professional is qualified, check the DAA or NSA websites.