US Department of Labor

“ General contractors usually assume responsibility for an entire construction project, but may subcontract to others all of the actual construction work or those portions of the project that require special skills or equipment. General contractors thus may or may not have construction workers on their payroll.
Building construction general contractors are primarily engaged in the construction of dwellings, office buildings, stores, farm buildings, and other building construction projects. ”

“ Establishments primarily engaged in managing construction projects for others on a contract or fee basis, but assuming no responsibility for completion of the construction project, are classified in Services, Industry 8741. Establishments primarily engaged in renting construction equipment, with or without an operator, are classified in Services, Industry Group 735.
Force account construction is construction work performed by an establishment primarily engaged in some business other than construction, for its own account and use, and by employees of the establishment. ”