I was just thinking about this question one fine day, when applying for university. The local university simply did not offer interior design, but just architecture. So I was thinking like maybe, the course in architecture would be all encompasing, but was not sure. My mindset was that an architecture education would be more superior to a interior designers' one due to the fact that the former undergoes a more rigorous training. Just browsing through the net, brought me some light on the issue. What exactly is the difference between architects and interior designers? Is it really just one who specializes in exterior and another in interior?

The term architect is very specific and regulated strictly in many countries. This means that it is agreed that unless you attend and graduate from an archictectual school, you cannot call yourself an architect. This would be some sort of protection for the architects and prevent abuse of its title. This is different from designers that it is loosely governed and anyone who graduated from some sort of design school or attended a design course, would be able to use the title designer.

I don't think its really comparing between architect and interior designer, but rather that they would actually need to work with each other. So, its not really architect versus interior designer. In the entire designing to construction process, both would handle roughly different areas or stages. However, at times these would definitely overlap, maybe in these circumstances, the architect would have more authority. I have no idea at all.

Of course, the designation isn't that important as compared to what the individual actual capabilities are be it that they are architect or interior designer. Both of them daple roughly in the same area, but at the same time, it can also be very different. For me I think it is important to be clear on the exact differences between the two professions. For example, if you want to revamp or renovate a shop or anywhere, indoor or outdoor, who should you approach?

Architects
Architects are primarily driven by the creative manipulation of mass, space, volume, texture, light, shadow, materials, program, and pragmatic elements such as cost, construction and technology, in order to achieve an end which is aesthetic, functional and often artistic. This distinguishes architecture from engineering design, which is driven primarily by the creative manipulation of materials and forms using mathematical and scientific principles.

Architecture as a profession is the practice of providing architectual services. The practice of architecture includes the planning, designing and oversight of a building's construction by an architect. Architectural services typically address both feasibility and cost for the builder, as well as function and aesthetics for the user.

An architect must thoroughly understand the building and operational codes under which his or her design must conform. That degree of knowledge is necessary so that he or she is not apt to omit any necessary requirements, or produce improper, conflicting, ambiguous, or confusing requirements. Architects must also understand the various methods available to the builder for building the client's structure, so that he or she can negotiate with the client to produce a best possible compromise of the results desired within explicit cost and time boundaries. The idea of what constitutes a result desired varies among architects, as the values and attitudes which underlie modern architecture differ both between the schools of thought which influence architecture and between individual practising architects.

Interior Designers
Interior designers plan many different spaces including, but not limited to; offices, airport terminals, theatres, shopping malls, restaurants, hotels, schools, hospitals, and private residences. Interior design is not to be confused with interior decoration which is focussed on choosing color palettes with complementary furniture, flooring, window coverings, artwork, and lighting. Today, interior designers must be attuned to architectural detailing including: floor plans, home renovations, and construction codes. Interior design draws on aspects of environmental psychology, architecture, and product design in addition to traditional decoration. An interior designer is a person who designs interiors as part of their job. Interior design is a creative practice that analyzes programmatic information, establishes a conceptual direction, refines the design direction, and produces graphic communication and construction documents.

Interior designers can specialize in a particular interior design discipline, such as residential and commercial design, with some developing expertise within a niche design area such as hospitality, health care and institutional design. In jurisdictions where the profession is regulated by the government, designers must meet broad qualifications and show competency in the entire scope of the profession, not only in a specialty. Designers may elect to obtain specialist certification offered by private organizations.

There is this blur or grey area that arises, thus emerge the use of terms like interior architect in the 1970s. At a more pragmatic level, the use of the term 'interior architecture' is a response to the uncertainties inherent in the title 'interior designer'. Its growth was due to a perception that by employing the rigour of architectual thinking together with the sensory understanding of interior design, a synthesis could be produced that was both intellectually and humanistically satisfying and which overcame the narrow specialisms of facade- driven architecture and context- free interior design that were prevalent at that time.

Interior Architecture bridges the practices of interior design and architecture so that professionals working in the field have a structureal and load bearing education with an emphasis on interior spaces. The field is similar to architecture in that it deals with structures and load bearing walls. It is similar to interior design in that it focuses on interior spaces.

Many references from wikipedia, The Fundamental of Interior Architecture, more reads from DL.