It is a common misconception that hardwoods are called hardwood because the wood is hard, while softwood is so named because they are soft. It is true that many hardwoods are more difficult to machine than softwoods, however the distinction actually has nothing to do with the hardness or workability.
Southern yellow pine, for example, is heavy dense softwood used for stair treads and large framing lumber. It machines and accepts fasteners in a manner like that of hardwoods. Walnut and poplar are common hardwoods, but they can be routed and sawn as easily as cedar or redwood.
Even pricing is not a good indicator of hardwoods or softwoods. More softwood is manufactured into building materials than furniture-grade lumber, but what does become lumber can be quite expensive. Take for instance; clear sugar pine lumber, it is just as costly as premium cherry or white oak.
Actually, the basic economics of supply and demand have more to do with lumber pricing than the particular species of wood or even its grade designation.
Choosing what to use –
Woodworking projects can use both softwoods and hardwoods. Generally, hardwoods end up as indoor projects such as wood furniture, trim-work, cabinetry and turnings because the wood grain and figures are highly desirable. Softwoods tend to become outdoor furniture, children’s projects such as tree houses and other sorts of utility or painted projects. These are merely general guidelines. If money is no object, you can build children’s furniture from practically any furniture-grad lumber you have.
The answer to – what species should I choose for a particular project? – is not cut and dried.