Question On A Couple Of Korea Stamps

I recently purchased a small lot of Korea. All the following are labeled individually in the purchase. My questions are on the following. Scott number 373 vs. 1076. They look identical to me. Scott calls 373 dark and light green and 1076 brown and light green. I've looked under the microscope and still see no color difference. Can anyone advise if there is a discernible visual color difference on these - otherwise I can only assume they are mislabeled. Facing the same issue on 374 vs. 1077 light green and buff vs. light green and salmon. All are on granite paper and perf the same. I do not think it would do any good to post pictures as they all look alike without the monitor color degradation. Just trying to see if it is one of things where if I see it I would know it.
Thanks for your help.

I have Scott 373 in my collection, but no 1076. The vertical lines at the sides and the denomination are printed in the dark green ink. The wavy line background is light green. I would think that the difference between dark green and brown should be discernible. Is there a dated postmark to help with identification? There is an 11 year difference in the issue dates.

I hope this helps.

Robert

Robert - Thanks for the help. I think I figured it out by looking at the back of the stamps. The later versions of both stamps have significantly more fibers showing in the granite paper. Still cannot see any obvious difference in the color definition on either though. Scott does have a foot note about the fibers.