The distinction between these careers isn't always clear-cut, and I think there is some disagreement over the use terms Interior Architect and Interior Designer. This is my understanding which might be incorrect in parts. I am an architect who works with outside interior designers occasionally.

Architect - Trained to design and oversee construction for a building and all of its components, including interior spaces. The training includes an understanding of building codes, structural systems and life safety. Architects can and do design interior spaces, but often on larger projects the interior design will be performed by a separate team who are more specially experienced in this work. Architects require a license to practice in every state, and the requirements are quite strict. It requires an accredited degree, internship, and examinations - typically takes from 8 to 10+ years from the start of study to get the license.

Interior Architect - Actually a type of architect who focuses on interior design work. They have the same background and training as an architect and understand building codes and construction. Some have a background in interior design separate from architecture, but some start out as architects and simply focus on interiors during their work. They tend to work on projects like Hotels, Office Tenant Space and Retail Shops where the focus is on creating functional interior spaces with a trendy or distinctive image. On new construction they work closely with the building architect - on renovations they are the lead architect.

Interior Designer - Not all states recognize this as a licensed profession, meaning it doesn't have the same standard education and training as architecture. There are voluntary certifications that demonstrate a certain minimum of education and training. At the top end, interior designers are professional designers who consider functionality and technical coordination with lighting, climate control, etc and who can work closely with an architect when needed to get a project built.

Interior Decorator - As far as I know there are no licenses or certifications for this, anyone can decide to provide interior decoration services without any qualification. Since they have no training in planning or construction they tend to be focused on selecting finishes and furniture for spaces as built.

To answer your first question, a person can be both an interior designer and an architect; and this is actually quite common.

If you want to get more information you should contact interior designers or firms that you admire. Some of the big firms that provide commercial interior architecture / design services include Gensler, HOK, RTKL, SmithGroup. There are many many others, you should look through design magazines to get a sense who they are and what the work they do is like.

On men/women in architecture: It's a noted problem in architecture that men greatly outnumber women, especially in more senior positions. Do a search on this site - there were a few thoughtful discussions and feature articles about this last year.

^the number disparity isn't really that significant in non-senior positions.

interior architect is nothing more than interior design trying to re-brand itself. Enjoy placing drones in cubicle farms and arguing over fabric patterns.

I have a degree in Interior Design, and I took some architecture courses as electives, including a graduate course in the History of Architecture, at UT Austin.  In the architecture classes, 90% of the students were men; in the interior design classes, 90% were women, but this was in the late 1980s in Texas, and things may be different now or in different geographic locations.  My roommate (from Hong Kong) while there was the prima donna of the architecture department, but he would ask me for help when he had to design a kitchen space.  I got the idea that architects like to design monument to their egos (at least some do) and are primarily concerned with how the building looks from the exterior.  Again, not all architects are like this, but there are plenty who are.  The exceptional architects will consider the interior architecture to be as important as the edifice.

After getting my degree in Interior Design, I got a job at a furniture company, and after a period of time, I was able to become part of the design team, and I gave up on having a career in ID.

• Interior architecture is the balancing of the art and science of designing an interior space taking into account all elements of the build. However, a designer with training in interior architecture cannot call themselves as such unless they have the professional accreditation from an architectural body.
• Interior design is a broad ranging profession taking into account all aspects of planning and designing interior spaces in the built environment. The role of any two interior designers can vary greatly.
• Interior decoration is concerned solely with the decoration or ‘art’ of a space including soft furnishings and color schemes.

An interior designers specialise in interior spaces - colours, materials, furniture. An architect specialises in creating buildings - form, space, use. Architects can create interiors though not usually as well as interior designers. Interior designers cant usually create buildings.

Just ask yourself what do you really want to do and then do it. But note that architecture can be not massively creative for many people who get stuck in a cad role, and interior design is very creative but very limited in scope - you wont be responsible for the space and form of the space a lot of the time as that will come from the architect.

Architecture is far larger enterprise and you need to be able to handle leadership, stress and responsibility for some very big projects sometimes for many months, interior design is generally much smaller but with a faster turnover of work I presume.

I had never even heard of the term 'interior architect' before this post. How can someone be an 'interior architect'? Makes no sense.

oops, the salesman vanished 

In simpler terms, Interior is all about the interior things and architect is all about construction of buildings and homes.  And interior decorators are not even licensed to do so. No planning, no training. And yes one can be both interior designer as well as  architect the only thing is that he should have basic knowledge and skills of both.

Mcb1019 these are very well thought out questions, which I don't think were completely answered on this thread.  You seem very analytical which is great.  What did you decide?  How did you come to your decision?

If you go to an accredited architecture school as an undergraduate this may lead you to have a lot go options upon your graduation. Unlike most college majors you aren't simply an architect upon graduation. You can work in an architecture office as an intern of some sorts and work your way up in the ranks but you will always be underneath someone without the bachelors or masters. You have to have an additional year or additional two years. There is logging lots of hours, and then several exams to be completed before becoming a 'licensed architect'. Generally, architects can do it all but interior architects and interior designers can really only work on parts of a whole project. Think of the undergraduate architecture degree as a design degree. If you aren't satisfied with becoming an architect after four years of undergrad you simply dont go back for the the addiotnal year. You can go on and do a lot of different things that may or may not pertain to architecture. 

Where I work there are interior designers who studied that and those that studied architecture but found a lot of what the "architects" do boring and ended up dedicating themselves to interiors entirely. Generally, it would be easier to study architecture and switch to interiors than the other way around. If you want to do both that will depend on the type and importantly, the size of firm, you work for. One thing that I'll point out that could be an factor in what you decide is the pace and turnaround of projects. Interior architects/designers often end up working on more projects and cycle through them faster. Depending on the size of the projects you work on an architect could be working on one or a few buildings for years. 

Even though this post is several years old, Ill add a little for current information. 

There were three options for people matriculating out of high school where i'm from. You could go to the one in-state Architecture school for an accredited degree, a different school for an unaccredited degree in interior architecture, and another different school for an unaccredited degree in interior design. At the end of the day, the people who couldn't get into the architecture program ended up at the other schools. I think its personal preference really. You can do all of these things with an accredited degree in architecture so if you want options that's the way to go IMO but also architecture itself is a lot more technical than the others and requires substantially more knowledge, work, schooling etc.  

hi I am a gcse student atm and I am doing  gcse next year and will be applying to college and I am not sure what subjects to take and I am interested in  architecture/interior design as a career can anyone help me out