The ABS wage price index tracks the pay for a fixed set of jobs, so it is not distorted by changes in who is employed. US average hourly earnings is simpler and can jump when low-paid jobs are lost, raising the average without anyone getting a pay rise.
Why it matters
Wages are the largest cost for most businesses and the main income for households. Wage growth above productivity growth plus the inflation target tends to keep inflation up; below it, real incomes fall.
See the data: Australian wage growth, US wage growth.
General information, not advice.