In construction business, it's common to:
Subcontract subprojects or activities to another company, which does the work you. If you subcontract a subproject or activity, you purchase a service from a vendor. This service usually includes a combination of labor, equipment, and materials.
Hire external persons to do (a part of) the work for you. If you hire an external worker, you purchase a service from a vendor. This service usually includes only labor.