The shadow is known to be cast by an opaque object especially when there is a source of light and the shadow will be blocking the light from reaching the ground. The shadow many change its size and length depending on the light source.
The shade is known to be the dark side that is created by the shadow. There are a lot of trees that can provide shade to those who are feeling very hot because of being exposed to the outdoors for a long time. When you are under the shade given by the tree, you will get a bit of relief from your discomfort.
Shade and shadow are the two terms often heard in the art world. If you want to create a pencil drawing of something, then you would then shade the areas to show light and dark and give the picture some depth and make the items in the picture seem three dimensional. However, you can also shadow items where it looks like the item has cast a shadow on the ground or flat surface behind the item.
The sun or some form of light would need to be considered in front of the item in order for the shadow to be cast. Another similar definition of shadow is not used with art, but if you go outside, you can cast a shadow from the sun onto a sidewalk.