Shade can refer to any dark area in which sunlight or other bright light is blocked. Shadow refers to the dark shape that appears on a surface when an object blocks sunlight or other light.
Usually, when you use the word shade, you are talking about a somewhat large area of darkness, and the object blocking the light is not so important, or the shape of the shady area is not so important. Below are some examples of how it is used.
Usually when you use the word shadow, you are talking about the specific area of darkness and often you are also talking about the person or object creating the darkness. Sometimes you are talking about the exact shape of the darkness too. Below are some examples of how it is used.
Sometimes the word shadow is used in a figurative or nonliteral way to describe one person’s power or reputation as stronger than someone else’s and make the other person seem less important or less impressive. It is also used to talk about an unhappy or gloomy situation. Below are some examples of how it is used in these ways.
For more uses and example sentences, visit the entries for shade and shadow in the Learner's Dictionary. I hope this helps.