What is the difference between platyhelminthes and nematoda?

Hint: Platyhelminthes and nematoda are two major invertebrates phyla in the animalia kingdom that show difference in their morphology. Though they are simple, they perform vital body functions of life.

Complete answer:
Let us first infer both the kingdoms.
PLATYHELMINTHES are also called flatworms with a dorso- ventrally flattened body. They are endoparasites found in animals. Flatworms are usually bilaterally symmetrical, triploblastic, and acoelomate animals with organ level of organization. Hooks and suckers are present in the parasitic forms. Some of them absorb nutrients from the host directly through their body surface. Specialized cells called flame cells help in osmoregulation and excretion. Sexes are separate, fertilization is internal and development is through many larval stages.
NEMATODES- They are called roundworms. They are free living, aquatic and terrestrial or parasitic in plants and animals. Roundworms have an organ system level of organization. They are bilaterally symmetrical, triploblastic and pseudocoelomate. Alimentary canal is complete with a well developed muscular pharynx. An excretory tube removes body waste from the body cavity through the excretory pores. Often females are longer than males. Fertilization is internal and development is direct.
Differences between Platyhelminthes and Nematoda:


Note:
Despite the difference in structure and form of different animals, there are fundamental features common to various individuals in relation to the arrangement of cells, body symmetry, nature of coelom, pattern of digestive, circulatory or reproductive system. These features are the basis of animal classification.