Service evaluation seeks to assess how well a service is achieving its intended aims. It is undertaken to benefit the customers using a particular product service and is designed and conducted with the sole purpose of defining or judging the current service. 
The results of service evaluations are mostly used to generate information that can be used to inform local decision-making.
Audit usually involves a quality improvement cycle that measures care against predetermined standards (benchmarking), takes specific actions to improve care and monitors ongoing sustained improvements to quality against agreed standards or benchmarks.
When organisations need answers fast, service evaluation and/or audit may be used to capture ‘real-time’ data and quickly move findings to create tangible practice change. An audit is like ‘taking the pulse’ of an organisation—it can produce results fast. As we check the organisational pulse against an expected range of normal we need to be sure we use the best approach to get an accurate reading so that our response is based on good data. This means no matter what the project scope or purpose, your project design should produce high-quality information about customer service and comply with ethical standards that protect consumers.