Scalability provides the ability for a cloud service to accommodate growth in workload by enabling the addition of resources in a seamless manner, thus maintaining performance levels. Unlike elasticity, which quickly adjusts to short-term fluctuation in demand, scalability ensures that the system's capacity can grow over time as needed. Cost efficiency and infrastructure resilience, while benefits of the cloud, do not directly describe a system's ability to maintain performance in the face of long-term increased demand.