First differing feature: A Annelida has a segmented cylindrical body, whereas a Nematoda has a cylindrical body but with tapered ends.
Second differing feature: An Annelida has a well-developed mesoderm, as opposed to a Nematoda which does not have a mesoderm.
Extra differing feature:
Annelida = 8-10 inches long
Nematoda = 4 feet or greater
Hope this helped!