What is the difference between a hardwood and a softwood? It might come as a surprise to find that it has nothing to do with the firmness of the wood itself which is generally all pretty hard. What type you use depends very much on what you are looking to build. The term softwood and hardwood is actually more of a botanical reference rather than of density. A hardwood is the wood that comes from a deciduous tree, a tree that sheds its leaves in winter i.e Oak and Beech. A softwood is a Conifer or evergreen that does not shed.
Whatever type of wood you need you should look to contact Timber Merchants Southampton based firm http://www.timbco.co.uk/ for all your requirements. There is still some truth to the term hard or soft. The evergreen does indeed have a less dense structure than the deciduous.
For external projects it is the hardwood that should be chosen. This is if you are looking to make a pergola, pagoda or shed. Softwoods are more pliable and are suited more for indoor projects. They are likely to for the basis of fibreboard and plywood. They can be used outside but need more protection via paint and treatments. However this does also apply to hardwoods if used outside for significant periods of time.