Amorphous allotropes of carbon :
∙ The atoms are arranged in an irregular manner which results in an indefinite shape.
∙ Examples: Coal, coke, lamp black (also known as soot) and charcoal.
Crystalline allotropes of carbon:
∙ The atoms are arranged in a definite order and this orderly arrangement of atoms is called crystal structure.
∙ Examples: Diamond, graphite and fullerene.