What is an engine?
The engine is at the heart of the search setup. When implementing search on the website, an engine is needed to define which results to present. An engine can be connected to the search index of one or multiple crawlers, for added flexibility. Read more about how to set up an engine here.
A lot of features are enabled and configured on an engine-bases. Because of these features, two engines with a big overlap in content can still end up working in very different ways due to the way in which tools have been applied. When looking at analytics and reports, the data here also appears on a per-engine basis in order to provide a more detailed view of the visitor activity.