What is the difference between the words “المكذبين” (the deniers) and “كاذبين” (liars) as they appear in Surat An-Nahl: 36-39?

The difference between "Al-Mukaththibin" (those who deny/disbelieve) and "Kadhibin" (liars) in the Quranic verses is that "Al-Mukaththibin" refers to those who denied Prophet Muhammad (peace be upon him) and what he brought. This appears in the context of commanding the disbelievers of Quraysh to travel through the land to see the fate of the nations before them who denied the messengers. As for "Kadhibin," it means that they were liars in their statement: "Allah will not resurrect those who die." This is a reproach to them on the Day of Resurrection, when they will know with certainty that they were liars.