Australian Apprenticeships can be done by anyone of working age with eligibility to work in Australia. There are no specific apprenticeships or traineeships just for adults.
Adult Apprenticeships usually refer to someone over the age of 21 when they start their apprenticeship or traineeship. This relates to things like wages and incentives, not to a specific type of apprenticeship program.
Apprenticeships and traineeships can provide a pathway to a career change, re-entry to the workforce, or can be used as a way to up-skill within your current industry.