Being one of the large 'ALL' islands, this one Still does not seem to be the most difficult, because modern composer differences sound more pronounced than for example Romantic. [All Modern]

This is a simple island, although both composers are known for popular tunes.

The key to this island is Weill opera sound, which is not that jazzy as Gershwin, but rather popular. (Gershwin, Weill)

Gershwin sounds more clear and jazzy.

Milhaud also has jazz feeling, but sounds more polytonal, dissonating, percussive and brazil dance.

Only Gershwin has vocal, piano concerto, lullaby for strings in this game. (Gershwin, Milhaud)

Gershwin should be no problem to guess. While two others are both russian and both can sound wide and melodic at times. Lighter pieces with pizzicato and melodic percussion are more common for Tchaikovsky, while Shostakovich usually sounds more serious and depressive. (Gershwin, Shostakovich, Tchaikovsky)

Rachmaninov is post-romantic and beautiful. Gershwin is jazzy. (Gershwin, Rachmaninov)