1, the size relationship in the same project (from big to small):

Single project unit engineering division engineering subdivisional work.

2. A single project refers to a project with independent design documents that can independently exert its production capacity or benefit after completion. Also known as an engineering project.

For example, houses in production workshops, office buildings and factories; Teaching building, canteen, dormitory, etc. It's part of an infrastructure project.

3. A unit project refers to a project with independent design and construction conditions, but it cannot independently exert its production capacity or benefit. It is an indispensable part of a single project.

For example, the single project of the production workshop is composed of plant engineering, mechanical equipment installation engineering and other unit projects. Building engineering can also be subdivided into general civil engineering, pipeline engineering, electric lighting engineering and industrial pipeline engineering.

The difference between the above two mainly depends on whether the overall benefit or production capacity can be independently exerted after completion.

4. Sub-project: The unit project is divided into sub-projects according to the type or main part of the project. Such as: foundation engineering, main engineering, electrical engineering, ventilation engineering, etc.

5. Sub-projects: According to different construction methods, structures and specifications, sub-projects are divided into sub-projects. Such as the installation of cast iron pipes, steel pipes and valves in earthwork, reinforcement engineering and water supply engineering.