비(bi)
Water falling from the sky in liquid form
When to use
Everyday talk about rainy days, Weather forecast mentioning rain, Describing rainy weather
The nuance
비 falls when the temperature is above freezing, as liquid water droplets. Unlike 눈, 비 does not freeze and falls as rain.
눈(nun)
Ice crystals falling from the sky in solid form
When to use
Talking about snowy days in winter, Describing snow accumulation, Weather forecast mentioning snow
The nuance
눈 falls when the temperature is below freezing, as solid ice crystals. Unlike 비, 눈 can accumulate on the ground.