Answer : The word 'decorator', which is the noun form of the verb, refers to someone who makes (not necessarily interior) decorative changes to a home. It's often narrowed to refer mainly to people who are in charge of arranging and displaying pieces of art and knick-knacks - these people can also be referred to as 'interior decorators.'
However, there are other ways that somebody could qualify as an interior decorator. There have been instances where architects or construction managers might take on that role for larger projects. For instance, builders might need decorators when they're working on large construction projects like airports or airlines companies' headquaters.