“Superstition is to religion what astrology is to astronomy; the mad daughter of a wise mother.” ‒ Voltaire (1694-1778).
Some say that all religion is superstition.
They can look alike. Carry a rabbit’s foot or a rosary. Wish upon a star or pray to a great spirit. Knock on wood or light a candle.
They can be intermingled. If you spill salt, throw a pinch over your left shoulder to blind the devil waiting there. If someone sneezes, say “bless you” to stop the devil from claiming their freed soul. If you break a mirror, bury the pieces under a tree during a full moon to renew your damaged soul so it can fight off bad luck.
They can slip from one to the other. Black cats: sacred in ancient Egypt; bad luck now. Knocking on wood: ancient tree worshippers laid their hands on a tree when asking for favour from the spirits that lived inside it; now a superstitious knock to acknowledge luck and keep it going. Rabbit’s foot: part of an ancient Celtic coming of age ceremony; good luck now.
Some say one person’s religion is another’s superstition, and maybe that could make for a blurry line between them. But I think the line is usually pretty clear: superstitions are driven by fear and ignorance; religions are powered by love and creativity.