While I am not sure what qualifications either involves, I do know that an interior designer will look at your plans (or you home) and make suggestions such as moving a staircase for better flow or eliminating a redundant closet, suggesting that a shower be enlarged, structural things. An interior decorator is more about finishes, furnishings, colours, flooring, etc.

moving a staircase for better flow or eliminating a redundant closet, suggesting that a shower be enlarged, structural things

Isn't that what an architect does?

When we were doing our offices we used an interior designer. She made suggestions, designs, and sketches about the office layout, placement of equipment, and general people flow. She also made suggestions and designed the offices to enhance the workspaces and accommodate the workers needs. Separately, an interior decorator worked with her and us on picking the flooring, furniture and window treatment.

In my own experience, we designed our house ( a from the floorboards up reno incorporating the original footprint plus a large addition, a draftsman fine-tuned our ideas and drafted our plan and an interior designer suggested some changes as I mentioned above. I should have said in my first comment that I was basing my answer on personal experience.

Facts

According to the American Society of Interior Designers (ASID), 26 U.S. states have laws recognizing interior designers. Some of these states require individuals to be licensed to work as interior designers. Although interior design laws and licensing requirements vary throughout the U.S., those individuals who hold the title of registered, certified or licensed interior designer have met the minimum requirements to offer their interior design services in their state.

States Requiring Licensure

The states that require interior designers to become licensed are known as practice law states. States including Alabama, Florida, Louisiana and Nevada have established agencies that enforce licensing requirements for individuals working as interior designers and regulate the practice of interior design along with the use of designated titles for these professionals. Although all these states require interior designers to obtain a license, individuals who conduct their work under the direct supervision of a licensed interior designer or only work with residential clients may be exempt in some states.

Basic Licensing Requirements

Each practice law state has different education and experience requirements for licensure, but all these states require interior designers to pass the exam given by the National Council for Interior Design Qualification (NCIDQ). To take the NCIDQ exam, applicants must have at least six years of combined interior design work experience and college-level education. Although the NCIDQ offers applicants several ways to meet these requirements, the council does not approve applicants who have not completed one of the six available eligibility routes.

There is a bit of gray area because some "interior designers" are able to hire enough staff to fulfill some of the requirements that they themselves do not have. My own ex-boss was inducted into the Interior Design Hall of Fame, but she only had a degree in art and hired an interior architect to do the architectural drawings and specs. We also had a client in England who was a multi-billionaire who decided to call herself an interior designer and mainly decorated the yachts of her best friends. She had a large staff who did all the technical work.

For the most part, what Fun2BHere wrote is accurate, but there are a few very high-end exceptions.

An interior designer works closely with architects to design the interior space and has a good amount of experience within the construction field. Decoration or decorating, on the other hand, is the furnishing of space with beautiful or fashionable things while working within its functionality. An interior designer is your best choice if you’re working on a remodel and require guidance beyond aesthetics. They can help you redesign your space from the ground up, as well as navigating day-to-day details like working with contractors. When I was changing the design my kitchen, the designer I was working with helped me choose some amazing coloured glass splashbacks from https://www.diysplashbacks.co.uk/custom-splashback so I would advise anyone who is looking to change their home to look for an interior designer.

Google is your friend.

As mentioned above but in Canada the tiltles are used interchangably often . I am an ID and to be honest the decorating part of a home redesigned by me is not my most fun part. I have a friend who is awesome at decorating so I often turn that job over to her.

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