I can't tell if you're trolling. I've never heard of an M.Int.Arch but interior design is different from architecture. Not a licensed profession...and also, I hear, much more lucrative. Though of course there will be overlaps in the concepts and skills you learn.

Hey, you should wait for the GSD to start its furniture/interiors program. :P

Not trolling. Found an M.Int.Arch program at UCLA. It seemed so different and never really heard of an M.Int.Arch degree either so that's why I was asking. I figured it was still within the realm of design and that basic concepts were still taught in the program. 

But this is the point of the question; if it's that different?

Interiors much more lucrative? 

It can be more lucrative, depending on how it's practiced, because as a non-licensed practice, interior designers can take commissions from the manufacturers whose products they specify (or can straight up buy and resell these things at a markup), whereas the licensed profession of architecture forbid this.

Ofc, there are architects whose work could probably mostly be done by interior designers/architects, and larger architecture firms may have staff who work on interiors only. But the fact that one is a licensed profession and the other is not is huge--not as a value judgement, but just as a general descriptor of conditions in school and in practice.

A clearer way to say this might be to say that the work of certain interior designers and certain licensed architects might look quite similar, as in the case between psychiatrists (who are MDs, who can prescribe drugs, and who are subject to specific professional requirements and licensure) and psychologists (who could have a wider range of backgrounds and kinds of practices). But, as for psychiatrists and psychologists, there are also hard lines that distinguish one profession from the other, in school and in practice. Look at the wikipedia articles for the two, or at the websites of the AIA or NCARB.

You don't have to get licensed if you go to architecture school, though--and in that case your work could be more like the work of any number of other fields.