A design engineer is a general term for a person who may be involved in any of various engineering disciplines including electrical, mechanical, chemical, textiles, aerospace, nuclear, manufacturing, civil, systems, and structural /building/architectural. Design engineers tend to work on products and systems that involve the use and adaption of complex scientific and mathematical techniques. The emphasis tends to be on utilizing engineering physics and sciences to develop solutions for society.
While industrial designers may be responsible for the conceptual aesthetic and ergonomic aspects of a design, the design engineer usually works with a team of engineers and other designers to develop conceptual and detailed designs that ensure a product actually functions, performs and is fit for its purpose. They may work with industrial designers and marketers to develop the product concept and specifications to meet customer needs and may direct the design effort. In many engineering areas, a distinction is made between the design engineer and the planning engineer in design; analysis is important for planning engineers while synthesis is more paramount for design engineers.
When the design involves public safety, the design engineer is usually required to be licensed, for example, a professional engineer in the U.S and Canada. There is usually an "industrial exemption" for design engineers working on project internal to companies and not delivering professional services directly to the public.
Design engineers may work in a team along with industrial designers to create the drawings necessary for prototyping and production, or in the case of buildings, for construction. However, with the advent of CAD and solid modeling software (such as PTC Creo, SolidWorks, Onshape, SpaceClaim, Solid Edge, KeyCreatorAutodesk Inventor, boss, NX, and CATIA), the design engineers may create the drawings themselves.