The main difference between crystalline solids and amorphous solids is that crystalline substances have characteristic geometry while amorphous solids do not. In other words, crystalline solids have a definite and orderly shape and amorphous solids do not.
While crystalline solids have a sharp melting point, amorphous solids are softened and melted over an unspecific range of temperatures. For example, glass is gradually softened and melted without undergoing an abrupt change to the liquid state. During the process of crystallization, amorphous solids experience a smooth cooling curve with a continuous drop in temperature. When crystalline substances undergo the crystallization process, they experience two breaks in their cooling curve. The two breaks indicate a period of a constant temperature instead of a continuous decrease in temperature.
The structure of a crystalline solid is much more rigid than the structure of an amorphous solid. Amorphous solids are irregularly broken while crystalline solids cleave along definite planes.
Another difference between these two types of solids is crystalline solids are anisotrophic and amorphous solids are isotrophic. Isotrophic means the solid's properties are independent of the direction in which they are being measured. Anisotrophic means the solid's properties are in different directions. Cellophane is an example of an amorphous solid. Copper is a common crystalline solid.