You would think that a classification of either hardwood or softwood is determined by the actual feel of the wood—but it isn't. The difference between the two actually depends on the tree's structure. Hardwood comes from trees known as angiosperms, which are flowering trees with enclosed seeds like apples or walnuts. Therefore, hardwood includes ash, aspen, balsa, birch, cherry, elm, mahogany, maple, and oak. Softwood comes from trees known as gymnosperms, which have uncovered seeds that typically blow away from the tree once they fall off. Examples include cedar, pine, and spruce. By this definition, it's easy to see that you can't simply go by the feel of a piece of wood when determining its hardness. For example, balsa, which is classified as a hardwood, is actually one of the least dense and "softest" (to the touch) woods of all.