You may be surprised to learn that the difference between hardwood and softwood is not in their names, meaning that hardwood is not necessarily denser than softwood. For example, Balsa wood is classified as hardwood, but it’s actually one of the softest and least dense types of wood. Another example is Yew wood; it’s classified as softwood but it’s a lot tougher than many hardwoods.
Classifying a wood as hard or soft is dependent on the seeds produced by the tree. For example: if the seeds produced by the tree have a coating (like fruit or a shell), that wood is classified as hardwood. If the seeds have no coating and are dropped onto the ground, that wood is classified as softwood.