I believe the TFT.h include file that comes with the TFT Touch Shield has a mistake in the definition of the color green. Line 38 says:
#define GREEN 0x7e00
Given that the colors are defined by 5 red bits, 6 green bits, and 5 blue bits, green would be:
00000 111111 00000, in hex 0x07e0
So I think the line should say:
#define GREEN 0x07e0
Looking at both on the screen, the corrected green is more vibrant shade.