The key difference between these three categories of identifiers are:
- URI and IRI are the terms for any type of identifier used to identify a resource on the Web.
- URL is the term for any type of URI that can be resolved or de-referenced to locate a representation of a resource on the Web (e.g., Web page, file, image, etc.)
- URN is the term for a specific type of URI intended to persistently identify a resource
(i.e., an identifier that will never change no matter how often the resource moves, changes names, changes owners, etc. URNs are intended to last forever.)
More Information#There might be more information for this subject on one of the following:
- [#1] - DID (Decentralized Identifier) Data Model and Generic Syntax 1.0 - based on information obtained 2016-12-01-