Implantation bleeding typically occurs around 10-14 days after conception and is characterized by light, scanty bleeding that lasts for a short duration. Minimal additional symptoms often accompany it. On the other hand, a miscarriage usually occurs after a positive pregnancy test and involves heavier bleeding, similar to a period that may last several days. It can be accompanied by severe abdominal pain, cramping, back pain, and the passing of tissue or clots. A negative pregnancy test or a sudden change in pregnancy symptoms may also indicate a miscarriage.