What industry does personal decoration belong to?

Belonging to the construction service industry.

Personal decorators are freelancers. You can also call it an independent individual. This is a laborer, a professional decoration worker and so on.

If it is a decoration worker who has signed a labor contract with the company, it can be called an employee. Decoration workers are waiting for work in the decoration market.

If you don't sign a labor contract with the company, you are generally called a temporary worker in the labor market.