observation vs imagination

I enjoy drawing from observation more than from the imagination because the drawing is more likely to be realistic and that is what i generally strive for. It is not necessarily easier because it requires a lot of attention and focus. Drawing form imagination requires me usually to try to remember and visualize what something looks like. I do not think one approach is easier than the other, but that they both require different forms of effort and are equally difficult. However, I am definitely better at focusing and paying attention than i am at remembering and visualizing details.