Stage 4 has just a slightly darker green at the bottom of the image; I wanted to get that bit of grass right before moving on the more complicated parts of the print.
Stage 5 has a darker green over the rest of the picture.
These photos are deceiving: the two plain green patches in the bottom left and right are the same colour in both stages, but the second looks lighter and much yellower now it's against the darker green on the rest of the print.