Contrary to the name, softwood trees can often be harder than hardwood trees. Douglas fir, a softwood, is harder and stronger than many hardwoods, while balsa, technically a hardwood, is much softer than even most softwoods.
The difference between softwood and hardwood is found in the microscopic structure of the wood. Softwood contains only two types of cells, longitudinal wood fibres (or tracheids) and transverse ray cells. Softwoods lack vessel elements for water transport that hardwoods have; these vessels manifest in hardwoods as pores. In softwood water transport within the tree is via the tracheids only. Some softwoods, such as pine, spruce, larch, and Douglas fir, have resin canals, which provide transport of resin as a defense against injury.
In general softwood is easy to work: it forms the bulk of wood used by humans. Softwood has a huge range of uses: it is a prime material for structural building components, but is also found in furniture and other products such as millwork (mouldings, doors, windows). Softwood is also harvested for use in the production of paper, and for various types of board such as MDF. The finer softwoods find many specialty uses.