Public Work vs. Private Work
The fundamental distinction between government-funded construction, subject to [[concept-prevailing-wage|prevailing wage]], [[concept-certified-payroll|certified payroll]], bonding, and formal public bidding requirements; and privately funded construction, governed primarily by whatever terms the private parties negotiate into their own contract.
Why it matters
Because public work carries a distinct set of legal requirements that simply don't apply on private work, a contractor moving between the two has to operate under two different rulebooks: a mechanic's lien, for example, generally isn't available as a remedy against public property, so unpaid subcontractors on public work rely on a payment bond claim instead of the lien rights they'd have on a private project.
On a real project
A general contractor completes a private office building using a standard negotiated contract with no prevailing wage or public bidding requirements, then moves directly into a public library project that requires competitive public bidding, prevailing wage compliance, and certified payroll reporting the private project never involved.
Who this matters most to
An Estimator has to build fundamentally different cost assumptions into a public bid versus a private one: prevailing wage rates, bonding costs, and compliance overhead all add cost that isn't present on comparable private work. A Contracts Administrator has to know which remedies (lien rights vs. bond claims) are even available to protect payment, depending on which category the project falls into.
Where this goes wrong
A subcontractor on an unpaid public project attempts to file a mechanic's lien the same way they would on a private project, only to discover liens generally can't attach to government-owned property. Without that remedy available, the subcontractor has to pursue a claim against the project's payment bond instead, a different process with its own notice deadlines the subcontractor wasn't prepared for because they assumed the same rules applied as on private work.