What is the defining difference between ‘troubleshooting’ and ‘advanced troubleshooting’?

Troubleshooting refers only to the process of following published maintenance procedures (e.g., Fault Isolation Manual (FIM), Troubleshooting Manual (TSM)) to identify defects (Reference: Part 66 MOS, Page 4). 

By contrast, advanced troubleshooting refers to fault diagnostics which are “beyond the bounds of maintenance manual fault diagnosis guides”. (Reference: https://training.gov.au/Training/Details/MEA323)

In simple terms, advanced troubleshooting is done where there is no specific guide to follow, while troubleshooting is done following a published procedure.

It should also be noted that troubleshooting is typically required for Units of Competency at the Certificate IV level, while advanced troubleshooting applies to diploma level Units of Competency.