Interior design is the art and science of understanding people's behavior to create functional spaces within a building.
Decoration is the furnishing or adorning of a space with fashionable or beautiful things.
In short, interior designers may decorate, but decorators do not design.
Interior Decorators & Interior Designers are two seperate professions.
"Interior Decorators" are mentioned as an exception for filing ITR 4s
BUT
Can "Interior Designers" file ITR 4s?