What differentiates Architectural Engineering from its component disciplines is the effort to understand and design for the integration of all the building systems. Civil Engineers, for instance, can and do design the structure of a building. The Architectural Engineer with a specialization in structures will understand and accommodate not only the structural requirements for a building, but also the Architectural, HVAC, Plumbing, Electrical, Transportation, Acoustic requirements - only the most common of those usually considered.
A common confusion is the distinction between Architecture and Architectural Engineering. Architects are responsible for the form and appearance of a building with a focus on the way that people use and experience the spaces of the building. The Architectural Engineer is responsible for ensuring that "the building works" - that it stands up, that the HVAC system operates, that light and power are delivered as needed. Architectural Engineers use primarily the tools of engineering to achieve optimum system selection and sizing within the overall constraints usually set by the Architect.
The major specializations for an Architectural Engineer are: