There is no difference between jade and jadeite, as jadeite is one of the two variations of the gemstone jade, the second of which is nephrite. Both jadeite and nephrite are gemstones that are popularly used in jewelry and ornaments.
Rather than being a difference, jadeite is one of the distinct minerals in the jade family. Both nephrite and jadeite have distinct chemical compositions as well as differing levels of hardness, density and different crystal structures. These differences were not discovered until 1863. Up to that point it was thought that jadeite and nephrite were the same substance.
Jadeite is the most sought after of the two forms of jade. As a result it is more rare and ultimately more expensive to buy. As a stone in jewelry, they are usually measured in millimeters, with larger stones being the more expensive to buy. It is found mainly in Burma and is mined almost exclusively to be used as a gemstone.
The most common color is green so it is commonly used as a green stone in jewelry. But jadeite also comes in other colors including red, yellow, orange and brown. The most sought after variant of jadeite, however, is imperial jade. It is transparent and is emerald green. The most valuable jadeite examples are green in color with little or no gray. They are usually quite smooth in appearance with most jadeite being cut in China. Some cutters still use traditional methods to turn raw jadeite into a gemstone. This involves using a hollow lathe made from bamboo rather than modern tools or equipment.