OLEDs are emissive devices so their spectrum is just the sum of the individual Red, Green and Blue OLED spectra, modified slightly by the touchscreen layer and anti-reflection absorption layer through which their light must pass.

The spectrum of an LCD display is just the spectrum of its white LED Backlight filtered through the individual Red, Green and Blue sub-pixel filters within the LCD panel.

As expected the OLED RGB spectra are relatively narrow with deep notches and wide separations between the Red, Green and Blue primaries, which results in highly saturated colors.

The Spectra of the Galaxy S I,II,III are very similar. The differences between them are due to their different White Point Color Temperatures. The Galaxy S III has the lowest Color Temperature at 7,860 K and has relatively more Red and Green compared to the Galaxy S I, which has the highest Color Temperature at 10,177 K and therefore has a more bluish White with relatively less Red and Green compared to Blue. The Galaxy S II at 8,656 K is in between.

The LCD RGB spectrum shown for the iPhone 4 is a broader filtered broadband spectrum from the White LEDs, which results in less saturated colors.