Architecture is the art and science of designing and erecting buildings. Architecture precedes architectural engineering by centuries in existence and leans more toward being an art than a science, although you must have some knowledge of construction methods and materials to work successfully. However, architects rarely construct and mainly focus on designing a building to meet its function. Architectural engineering combines all aspects of the building design and construction, involving mechanical, electrical and structural blueprints, calculations, and other notions of mathematical precision. It is a field that uses far more technology than its predecessor.
Architecture focuses more on the aesthetic design and the functional and spatial layout of buildings as opposed to the engineering that architectural engineering incorporates. Architectural engineers apply engineering principles to the construction, planning and design of buildings and other structures. You may find that architectural engineers use far more technology in their field than architecture, which is deeply rooted in artistic expression.
There are various fields of engineering such as mechanical, electrical, structural, plumbing, HVAC, lighting, acoustic and more. Architectural engineers focus in several areas such as the structural integrity of buildings, the design and analysis of heating, ventilating and air conditioning systems, the efficiency and design of plumbing, fire protection and electrical systems, acoustic and lighting planning, and energy conservation issues. An architectural engineer may have more knowledge and expertise in one area than another and may seek professional certification in that particular area of interest.
Architecture focuses on the spatial design of the building and whether or not it meets the demands of the user. Not much thought is given to other building aspects such as the structure, the HVAC system, the lighting and electric design, or the acoustic design. A team of professionals certified in these areas offer their expertise after this initial planning phase. There are different kinds of architecture such as landscape, health-care, governmental, residential, commercial, and educational architecture or types. Just like an architectural engineer, an architect may have more knowledge and expertise in one area and may seek professional certification in that particular area of interest.
The Big Difference
You could think of architectural engineering as being an extension of architecture. Architecture uses spatial planning to produce drawings (floor plans, sections, elevations, etc.) that are latter evaluated by a team of professionals certified in areas that fall within the field of architectural engineering. This team can be formed within an architecture firm or contracted out to a construction firm. Some architecture firms are also architectural engineering firms, which means they don't have to contract out their projects and they can remain in full control of a project from start to finish. The big difference between architecture and architectural engineering is the creative versus technical expertise involved.