I imagine that the main difference between landscape architecture and garden design would lie primarily in their respective scopes. Garden design has a specific focus, not necessarily on a smaller scale but on spaces more narrowly defined. These spaces are often private and associated with a particular building or group of buildings. Landscape architecture can also have to do with gardens, but its scope is much wider, including public spaces. Another main difference between the two is that a professional must be chartered by an official body in order to earn the title of landscape architect, whereas any professional or amateur may be referred to as a garden designer. Finally, it may sometimes be assumed that on balance, landscape architects might be concerned more with hard landscaping, and garden designers more with planting.