Why is the color of the moon so similar to the clouds? Why the moon looks like the cloud-structure on the blue sky among the clouds?
The Moon is a dark gray in color -- it reflects light poorly but uniformly. (Its color is about the same  as fresh asphalt!  It's albedo is about 12%)  Clouds are (usually) light gray with an albedo ranging from 10% to 90%.

Both the Moon and the clouds shine by reflected sunlight, so they're both the same color. (Clouds usually have a greater surface brightness owing to their lower albedo.)