[excerpt from Horticulture magazine, Spring Planting Issue, 2007: 16]
"Simply put, landscape architects have earned a university degree in their field. They are registered, regulated professionals who have been trained in the technical aspects that may be involved in large construction projects. A garden designer may be largely self-taught, though they may have had other training or even hold degrees in related fields, such as horticulture. They may or may not be well versed in construction techniques, though some are adept and could do a fine job of designing your patios, walks, or overhead structures.
If you feel that your makeover entails a lot of structural changes, such as adding new parking, terracing a problem slope, solving drainage issues, or building large elements, you probably want to hire the landscape architect.
Landscape architects, however, are not always great plantsmen. Generally speaking, garden designers are more plant oriented and may have great flair for making compelling combinations or choosing plants that suit challenging sites. Some landscape architects actually employ garden designers to do the plant selections once they have designed the space. "