I think Rick was trying to initially compare apples to apples where the posters have the same image (and it probably works best for daybills vs. inserts), not items where one country has totally different artwork than the other.
But the Creature one-sheet Mel posted is a great example of my usual complaint about Australian posters, poor tracing of the US-art with no detail/shading, colored with what looks to be chalk crayons.
Because Them! and Dinosaurus are both tri-color posters, it's definitely easier to make the argument for the Australian ones, but the Star Wars and Venetian Affair show more typical results when making the comparison.