How are pinworms different from other nematodes?  

Yes. Pinworms primarily cause itching around the anus. Other nematodes that cause human disease can cause many other illnesses such as bowel obstructions or jaundice. Pinworms do not cause this.
Pinworms. Pinworms are nematodes. The biggest difference from most of the others is that they are so small, usually just a 1/4 to 1/2 inch in length. The primary symptom they cause is anal itch. You can diagnoses them yourself by applying a 2" strip of scotch tape to your rectum/anus at night when you have the itching. You will see one or more 1/4 to 1/2 inch long filaments looking like white thread.