The Operator hires the drilling contractor to drill the well and pays the contractor for their services. Sometimes the Operator will have partners who share in the costs of drilling the well and will share in the production from the well. Those partners are called Working Interest Partners. They will also be on the hook for any costs required to keep the well operating.
Royalty Owners pay none of the costs of drilling or operating the well. The Royalty Owners will get their royalty percentage of the production from the Operator when the well produces.
For example, if the royalty percentage is 20%, the Royalty owner will receive 20% of whatever the well produces. In this case, the Working Interest owners pay 100% of the costs and only receive 80% of the production.