Internal hemorrhoids are classified by the degree of prolapse. I internal hemorrhoids don't prolapse at all. Grade II drop down with a bowel movement but then pop back up inside spontaneously. Grade III must be manually pushed back inside. Grade IV cannot be manually reinserted and are the most severe.
External hemorrhoids are always outside by definition.
They rarely bleed, but can cause embarrassing rectal itching and soreness. Rarely, a blood clot can form within an external hemorrhoid turning it blue. This thrombosed hemorrhoid causes sudden severe rectal pain and usually requires a trip to the Emergency Department or surgeon's office. Sitz baths, sitting in a few inches of warm water in a tub, several times a day may ease the pain of a clot enough that surgery is not needed. Diagnosis is an important first step in treatment.