An interior designer and an interior decorator may seem to be the same thing. However, in essence, they are two very different kinds of professions all together. Why is that? Read on to learn the answer. You will be very glad that you did. Especially, if you don't know the difference between the two, and have always wanted to know the difference. What is the difference between an interior decorator and an interior designer? First of all, they are often mistaken for being the very same thing, but they do have some existing similarities. Nonetheless, they are terms, which are not interchangeable.