Piles are mainly the swollen blood vessels while fissures are kind of cracks and fistulas are an opening of a cavity. Piles are mostly painless and unnoticeable. Fissures cause a lot of pain. In the case of fistulas, pus is discharged out of the anal area.What causes them? Hemorrhoids are presumed to be caused by repeated pressure in the anal and rectal veins. Anal fissures are caused by trauma to the anal canal usually during bowel movements and constipation. Anal fissures are also sometimes caused by inflammatory bowel disease or infection.