Class:-

• It is the assemblage of related orders. E.g.Order Primala, Carnivora etc. is placed in class Mammalia.

Phylum (Division):-

• Phylum (Division in case of plants): It assembles
  related classes.
  E.g., classes in Amphibia, Reptilia, Aves, Mammalia, etc.
  come under phylum Chordata.

Kingdom:-

• The assemblage of related phyla. It is the highest category,E.g. Kingdom Plantae, Kingdom Animalia etc.