The element that appears in Auden's painting, "Musée des Beaux Arts" but is excluded from Williams's poem ""Landscape with the Fall of Icarus" is the ship that can be seen floating in the sea that drowns Icarus.
Williams's poem was inspired on Auden's painting, and it included almost every element presented on the image: it refers to the villages ploughing the fields, it talks about the hot sund that warmed tha wax on Icaru's wings and then describes the sea that finally takes the young man's life.
However, there is no mention of the big ship that can be appreciated in Auden's painting.