Concept artwork can serve a variety of purposes, and it is important to provide the level of detail that will accomplish the overall goals. In some cases an elevation with just enough detail to illustrate the design is all that is needed.
This type of illustration can be created in a shorter time frame, and with some color and texture, it can establish the mood or feeling of the intended design. If the final objective is to delineate exact features of the project, a more detailed concept may better accomplish your goal.
This final result can create quite an impact. The artwork, however, takes longer to develop, and because of the level of detail, the design must be much more complete. Either one is very valuable when developing a concept, and selling the design to the parties involved.