An anal fissure is a tear that extends from the muscles that control the anus and clear on up into your anal canal.
Anal fissures typically happen after the anal tissue suffers damage due to hard bowel movements or whenever there is too much pressure being applied to the anal sphincters.
An Anal Fistula is an infected tunnel which is located between the skin and your Anus and is the muscular opening at the end of your digestive tract.
Anal Fistula's usually require surgery to treat.
Symptoms of an Anal Fistula are swelling, pain and discharge of pus or blood from your anus.