Hi, read through what each authority is about and see how their purpose links to child protection, then you'll be able to explain their role and responsibilities.
http://cssiw.org.uk/about/what-we-do/?lang=en
Neighbour and community duty of care for children and help to protect them by reporting concerns -
NSPCC
https://www.gov.uk/government/public...ance-for-wales
"Duty of Care: The duty which rests upon an individual or organisation to ensure that all reasonable steps are taken to ensure the safety of a child or young person involved in any activity or interaction for which that individual or organisation is responsible. Any person in charge of, or working with children and young people in any capacity is considered, both legally and morally to owe them a duty of care. " source Guidance for safe working practices for adults who work with children and young people 2009
Hope this helps
Best wishes