Carbon Allotropes differ in their atomic arrangement and hybridization:

• Diamond: Every carbon atom is $s{p}^3$ hybridized and bonded to four other carbons in a rigid 3D tetrahedral structure.
• Graphite: Each carbon is $s{p}^2$ hybridized, forming two-dimensional hexagonal layers. The fourth electron is in a $\pi$ orbital, which is delocalized (explaining conductivity).
• Fullerenes ($C_{60}$): These 'buckyballs' also consist of $s{p}^2$ hybridized carbons arranged in a spherical cage of hexagons and pentagons.