what what

sp2 and sp3 orbitals

what As carbon atoms form e.g. a graphite or diamond lattice, the electronic orbitals hybridize. It would be very hard to draw electronic densities in any way that the underlying lattice structure could be understood for tens of atoms in a solid sample. So we draw different bonding states in different colors.
what There are deep differences between diamond and graphite, the former is a hard insulator, the latter a soft conductor.

what sp2 orbitals - 3 in-plane nearest neighbours
in sheets of graphite, near right.

what 4 nearest neighbours in an
sp3 bonded diamond lattice, far right.