With the public cloud, you get pay-as-you-go pricing - you pay only for what you use, no CapEx costs. With the public cloud, you have self-service management. You are responsible for the deployment and configuration of the cloud resources such as virtual machines or web sites. The underlying hardware that hosts the cloud resources is managed by the cloud provider.
https://docs.microsoft.com/en-gb/learn/modules/principles-cloud-computing/4-cloud-deployment-models

Reference:
https://azure.microsoft.com/en-us/reservations/
https://docs.microsoft.com/en-us/azure/virtual-machines/linux/b-series-burstable
https://blogs.technet.microsoft.com/uspartner_ts2team/2014/10/10/azure-virtual-machines-stopping-versus-stopping-deallocating/