Greenland vs Australia: which is bigger?
Australia is bigger: 7,692,024 km² against 2,166,086 km², about 3.6 times the size of Greenland.
Drop Greenland onto Australia →Side by side at true size
Both drawn at the same scale on an equal-area projection.
And on the usual world map
On the usual world map it's the other way round: Greenland looks 3.7 times bigger than Australia, because the map inflates Greenland about 16 times and Australia only 1.25 times.
In numbers
Areas: official totals including inland water (UN Statistics Division via Wikidata). Outlines: Natural Earth. How Globegami works