Dear student,

CRYSTALLINE SOLIDS - The solids having a definite crystal shape and have long range of orderness.

AMORPHOUS SOLIDS - The solids having not a definite geometrical shape and have short range of orderness.

Crystalline solids are also called as true solids. And amorphous solids are called as pseudo solids.

Crystalline solids are anisotropic, that means, refractive index and electrical conductivity are different in different directions. While amorphous solids are isotropic, which means, they have same physical properties in all directions.

Some examples of crystalline solids are sodium chloride (NaCl), zinc sulphide (ZnS).
And some example of amorphous solids are rubber, plastic, glass, etc.