Diamond → is made up of only carbon atoms, these atoms have strong covalent bonds to 4 other carbon atoms. This causes diamonds to be extremely hard. This means it is used in high speed cutting tools
Graphite → is made up of only carbon atoms. Each carbon atom is covalent bonded to 3 other carbon atoms. One atom is delocalised in every 4 carbon bonds and is free to move and carry charge, this is why graphite can conduct electricity without being a metal. Graphite is soft and slippery because there are weak forces of attraction between layers
C60 fullerene → is made up of only carbon atoms, has weak intermolecular forces of attractions which take little energy to overcome so it has a low boiling and melting point. It cannot conduct electricity despite having delocalised electrons