Contractor
In short
Defined twice, for two purposes. The tax definition rests on modifying property; the licensing definition rests on being paid to build, repair, or demolish it.
In full
Two Arizona statutes define contractor, and they are not the same definition.
For tax, A.R.S. § 42-5075(S)(3) states that contractor is synonymous with builder and means any person or organization that undertakes to or offers to undertake to, or purports to have the capacity to undertake to, or submits a bid to, **or does personally or by or through others**, modify any building, highway, road, railroad, excavation, manufactured building or other structure, project, development or improvement, or to do any part of such a project, "including the erection of scaffolding **or other structure or works** in connection with such a project." It includes subcontractors and specialty contractors. The last sentence is the one that surprises people: for all purposes of taxation or deduction, the definition governs without regard to whether the contractor is acting in fulfillment of a contract.
For licensing, A.R.S. § 32-1101(A)(3) defines contractor around compensation and around a wider list of verbs — construct, alter, repair, add to, subtract from, improve, move, wreck or demolish — reaching anyone who does that work by or through others, or who directly or indirectly supervises others doing it, and reaching connection of a structure to utility service lines, metering devices or the sewer line and the provision of mechanical or structural service to it. It expressly includes subcontractors, specialty contractors, floor covering contractors, hardscape contractors, and consultants who represent that they can supervise or manage a construction project for the property owner's benefit, including hiring and firing specialty contractors, scheduling the work, and selecting and purchasing construction material.
Contractor is the umbrella term in that section, not the only one. Three parallel definitions divide the same activity by where it is performed: commercial contractor at (A)(2), covering the work everywhere except within residential property lines; residential contractor at (A)(10), covering it within residential property lines on houses, townhouses, condominiums or cooperative units and their appurtenances; and dual licensed contractor at (A)(4), covering either under a single license. That three-way split, crossed with the general and specialty scope tiers, produces six of the seven license classes at A.R.S. § 32-1102 — general engineering is the seventh. Residential contractor excludes an owner making improvements to the owner's own property under A.R.S. § 32-1121(A)(5).
The practical difference between the two statutes is scope. The tax definition is built around modification. The licensing definitions cover repair and alteration on their face. A person can be a contractor for licensing purposes on work that is MRRA and therefore outside the prime contracting classification entirely.
Being a contractor says nothing by itself about which classification applies. That is a property of the contract, and each contract is evaluated separately.
A.R.S. §§ 42-5075(S)(2), (S)(3), 32-1101(A)(2), (A)(3), (A)(4), (A)(10), 32-1102