Australia vs New Zealand: two Union Jack ensigns

Short answer:Count the stars. Australia has six white stars, including a large seven-pointed star below the canton. New Zealand has four red stars with white outlines and nothing under the canton.

Both flags are blue ensigns with the Union Flag in the canton and the Southern Cross on the fly. Two differences separate them reliably, and both are easy to check.

Side by side

Australia

Six white stars, including a big one under the canton

The large Commonwealth Star has seven points, for the states and the territories.
The Southern Cross is shown with five stars; four have seven points and the small one has five.
Ratio 1:2.

Full Australia flag page →

New Zealand

Four red stars with white borders, nothing under the canton

Each of the four stars has five points.
The fifth, faintest star of the Southern Cross is omitted.
Ratio 1:2.

Full New Zealand flag page →

How to tell them apart, in order

1.Look immediately below the Union Flag: a large white star there means Australia.
2.Check star colour — red-and-white stars mean New Zealand, all-white stars mean Australia.
3.Count the Southern Cross stars: five for Australia, four for New Zealand.

Worth knowing

Other blue ensigns with southern-hemisphere stars exist, including Fiji, Tuvalu and several Australian state flags, so check for additional emblems before concluding.