Do you notice it takes much longer time to complete the second test than the first test?
The first test is easy because the color and meaning of the word are congruent. There is no conflict.
The second test is hard because the color and meaning of the word are incongruent. This creates a conflict that the brain has to resolve
The reason why it takes longer is because the brain has to suppress the wrong answer that interferes with the right answer, before the right answer comes through.
The above demonstration does not even take into account the incorrect responses in naming the colors.If you let the wrong answer to slip through impulsively, without waiting for the right answer to come through, it's because the brain does not have enough inhibition to suppress the wrong choice.
The reaction time will increase with fatigue and/or inattention to the task, so if you retake the test, it will show slightly different reaction times and error rates.