quality management(quality management can be considered to have four main components: quality planning, quality control, quality assurance and quality improvement. Quality management is focused not only on product/service quality, but also the means to achieve it. 4uzhoj)
service level(Service level measures the performance of a system. Certain goals are defined and the service level gives the percentage to which those goals should be achieved. Fill rate is different from service level. Examples of service level: Percentage of calls answered in a call center. Percentage of customers waiting less than a given fixed time. Percentage of customers that do not experience a stockout. WK Alexander Demidov)