This may or may not be an explanation for the different colours…
Revision pages are distributed on colored paper, a different color for each set of revisions, with each changed line marked by an asterisk in the right margin of the page. The progression of colors varies from one production to the next, but a typical sequence would be: white, blue, pink, yellow, green, goldenrod, buff, salmon, cherry, tan, ivory, white (this time known as “double white”), and back to blue (“double blue”).
When the Assistant Director believes that there are more changed pages than are worth swapping out, the Script Coordinator may issue an entirely fresh script in the appropriate revision color. In some cases, usually before the start of principal photography, an entirely new “white draft” will be distributed in lieu of colored revision pages.