In general usage a raffle has a thiing as a prize. Hence the idiom, "Let's raffle it off."The thing might be an automobile, motorcycle, bicycle or some other often donated prize. A lottery might also have a prize, but it is usually associated with a money winning. A lottery, unlike a raffle, might often be a repetitive chance and provide for an increase of the prize in case there is no winner which requires that you buy another chance.