ITIL clearly states that services "… add value to customers by enabling results that customers want to achieve …". However, sometimes companies and employees focus on results rather than results, which sacrifices some of the value of the service. This leads to the question, what is the difference between an output and an outcome?
As ITIL indicates, an outcome is:
The official ITIL glossary does not specifically define the word output, but Table 3.3 in the Service Strategy book provides some insight. Basically an output is "What a service provider does".
An outcome in ITIL is a result for a stakeholder enabled by one or more outputs.
Services facilitate these results. Output and results are two different things. A service provider produces results that enable my consumers to achieve their results.
For example, I was a financial transaction provider for an organization. My main service (output) was a financial transaction for an organization. The (result) was their ability to recognize revenue.
There is a common example of a wedding photographer. The photographer takes pictures at a wedding, the output is a tangible photo like an event photo book. The result, is the result, a retention of your memory of that specific event.