Air Traffic Controller reported clearing an aircraft to land; but the aircraft landed on the parallel runway; resulting in a runway incursion and conflict with a vehicle that was operating on the runway.

Narrative

Aircraft X was approaching ZZZ from the east on VFR flight following; they were requesting full stop taxi backs. An airport operations vehicle was holding short of runway XXL waiting for a runway inspection. I instructed Aircraft X to enter left downwind runway XXR; which he read back correctly. I then cleared Aircraft X to land on runway XXR. I was unaware at the time; but he only read back 'cleared to land' without the runway assignment. A controller changeover then occurred. The relieving controller took the position and verified with Aircraft X that they were cleared to land on runway XXR; which Aircraft X clearly readback that they were cleared to land runway XXR. The relieving controller then told the airport operations vehicle to proceed onto runway XXL for inspection; which the operations vehicle did. Aircraft X then proceeded to land onto runway XXL while the operations vehicle was conducting their inspection. The separation between the aircraft and airport operations vehicle was at no point closer than 6000ft. Aircraft X was immediately told to exit the runway.Ensure a proper readback from the pilot.