The difference lies in Geng and Geng.

Geng and Geng are the names of ancient ten-day stems, but they belong to different chronological systems of stems and branches respectively.

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The branch is a nail, which belongs to the chronological system of the main branch in the old calendar (also known as the "Yellow Calendar"). This is the traditional chronological method in China. It adopts the method of combining trunk branches with twelve branches, including ten trunk days (A, B, C, D, E, G, Xin, N, and D) and twelve branches. This chronological method is often used to indicate the year of the lunar calendar, for example, 2023 is the "non-Chen year" of the lunar calendar.

Geng refers to Shen, which belongs to the current chronological system of cadres and branches (also called "lunar calendar" or "lunar calendar"). The current chronological system of trunk and branch is still based on the combination of ten heavenly stems and twelve earthly branches, with Jiazi, which began in 2637 in the Yellow Emperor, as the first combination, as the starting point, circulating once every 60 years. For example, 2023 is the thirty-ninth year of 2 1 century Jiazi, which corresponds to the year of the dry year.

Therefore, Ji Yi and Geng Yi are different time points corresponding to different chronology systems, and there are historical and cultural differences between them.