A Police Check will return a list of offences in a report to PetCloud about a person’s national criminal history.
A Blue Card working with children check is an ongoing assessment of a person’s eligibility to work or volunteer with children based on their known past police and disciplinary information. However, PetCloud are not told of the criminal history of the person. Only whether the card is valid. Blue Cards can be validated here: https://www.bluecard.qld.gov.au/onlinevalidation/validation.aspx
A blue card is valid for 3 years unless suspended or cancelled and is monitored in relation to child safety. ie matters relating to Child Protection (Offender Reporting and Offender Prohibition Order) Act 2004 or Dangerous Prisoners (Sexual Offenders) Act 2003 etc
While a police check is a point of time check. A new police check will be needed to show any new offences. Aa a brief example, a police check will record things such as child related matters, stealing, speeding and dangerous driving convictions, drug dealing, fraud, etc.
For example, offering House Sitting as a service involves staying in a Pet Owners home alone while they are away. You are in a position of trust with looking after people's personal property while they are away. So you would want to be free of fraud and theft convictions. Convictions of this nature has nothing to do with children, so a Blue Card won't suffice. For this you need a National Police Check as it focuses on searching for all crimes committed nationally and discloses this to PetCloud, rather than an assessment of your suitability to care for children.
You can get a Police Check here: https://petcloud.nationalcrimecheck.com.au/ it costs only $39.