An artificial reef is any submerged structure that either:
Enhances coral growth, or
Functionally serves as a coral reef in that given ecology or constructed purpose.
As such, a coral restoration project can be an artificial reef, but an artificial reef is not necessarily a coral restoration project (a site that cultivates coral specimen, for any number of reasons).
What are those reasons? Why do people build these structures? Sometimes its for food, sometimes its for tourism, sometimes its in the name of something less tangible, like biodiversity – each artificial reef has its own story, and it’s own purpose.