The major difference between an interior designer and an interior decorator is that an interior designer is more detailed and technical. From the onset, he imagines and considers how a space will be used and who will use it. He designs from scratch while having the finished project in his mind. On the other, an interior decorator is more focused on the surface layout of the designs. He cares more about how the decorations (paintings, furniture, etc.) appear to the eyes and less about how the space will be used.