Two questions, two systems
Quality control asks whether a specific material, layer, or element meets the specification. Cube results, density tests, bitumen content and alignment checks belong here. Quality assurance asks whether the contractor's methods, inspection and test plans, laboratories and competence are capable of producing conforming work consistently.
A project can pass a day's tests and still have a weak quality system. It can also have well-written procedures and still fail if field control is inconsistent.
What this means on site
Construction supervision therefore needs both. The team should witness sampling, review test frequency against the specification and keep non-conformance visible. It should also audit whether mix designs, calibration, method statements and hold points are actually in use.
Independent laboratory support is most useful when it is tied to those control points, not added as a parallel report that nobody uses to stop the work.
Records that later still make sense
Owners, lenders and future maintainers will ask why a pavement or structure was accepted. The answer should be recoverable from dated test results, inspection records and a quality system that was operating at the time, not from memory.
That is the practical difference: control proves a result; assurance proves the result was not an accident.
Technical writing on this website is for professional orientation. Project decisions require site-specific investigation, current standards and qualified engineering judgment.