What's the difference between a green dragon and a white tiger?

The main basis for seeing the geomantic omen of Yin House is the "Dragon" and "Cave" in the "Five Tactics of Geography" (including Tang Ming, Sand, Water and Direction). "Dragon" is not a real dragon, but a mountain range, a mountain. A "cave" is a grave; "Sand" is the mountain in front of the grave; "Water" is a nozzle; "Xiang" is the direction of the grave. In ancient times, the four directions around the tomb were named after four kinds of beasts, one for the convenience of memory, and the other for highlighting the dignity of ancestors and the dead. The names of these four kinds of beasts are Zak [. South], post-Xuanwu [North], Zuo Qinglong [East], and Youbai Lake [West]. Legend has it that the status of the four beasts is also different. The latter is the largest and the former is the second. There are two guards on the left and right, the left position is regarded as auspicious position and the right position as fierce position. So Zuo Qinglong is taller than the right white tiger.