A pergola or arbour provides shade and structure to a garden design. They also help to promote plant growth and look stunning with wisteria or climbing roses or they can also be left as beautiful and refined structures in their own right forming the perfect focal point.
A pergola could be described as an open sided room, somewhere to relax in the shade, but fully connected to the garden. An arbour can be made with an open roof, or have a solid roof to provide a place to shelter from the odd shower.