Difference between Miscarriage, still birth and labour

Miscarriage is the termination of a pregnancy that doesn't end in childbirth, of a fetus that weights less than 500 grams (1.1 pounds) or before 20 weeks of gestation are completed (An in-viable fetus)

Stillbirth can occur at 20 or more weeks of gestation, and it's basically the delivery of a viable fetus who died in uterus (No fetal heartbeat) or at any point before birth was successfully completed (Right after the umbilical cord is cut).

Labour is the process in which the uterus, cervix, and vaginal canal prepare to expel the products of conception (Fetus, placenta, amnion) after 20 or more weeks of gestation. It starts with contractions that produce cervical modifications (Usually, one to two contractions every 10 minutes for at least 1 hour) and ends with the expulsion of the placenta and amnion, and subsequent retraction of the uterus.