Water is liquid and snow is solid;
Water is "dense" and "uniform"; Snow is "loose" and "open" and consists of many tiny particles.
Based on the above differences, light energy enters the water and continues to spread in a straight line; But when the light shines on the snow, you can't "go into the snow and continue to spread in a straight line"
When the light shines on the water, most of it enters the water, and very few of it is reflected; When the light shines on the snow, a little light enters the snow, and most light is reflected.
The eye sees an object because the reflected light of the object is received by the eye. When an object does not reflect light, the eyes can't see the object, which is called transparency.
Besides "color", objects have color because they selectively absorb light.
White light is composed of various colors of light, and the object is green, because the object absorbs all other light except green light. If only green light is reflected, the object will be green, but snow will not absorb light, or snow will absorb light evenly (all components will be absorbed in the same proportion). The reflected light of snow will keep the proportion of components when the light is incident, so when white light shines on snow, the snow will be white. According to this principle, when red light shines on snow, the snow will be red.