A scent is a smell. Every house has a particular scent that is recognizable to people as belonging to that house.
Scent comes from the Latin sentire meaning "to feel, perceive, sense." The word was originally used in reference to hunting dogs, who track down animals by their scent. If you "pick up a scent," then you have a clue about something. If you wear a perfume, then you leave your scent in the air as you pass. Use scent instead of smell if you want to talk about a distinctively nice odor, like the scent of fresh-cut grass.