Manifest: A manifest file in computing is a file containing metadata for a group of accompanying files that are part of a set or coherent unit. (wiki)
Metadata: Metadata is “data that provides information about other data”. In other words, it is “data about data.” (wiki)
Artifact: A software build contains not only the developer’s code also includes a range of software artifacts. A DevOps artifact is a by-product produced during the software development process. It may consist of the project source code, dependencies, binaries or resources, and could be represented in different layout depending on the technology. Software artifacts are usually stored in a repository. (Jfrog)
Snapshot: A snapshot version in Maven is one that has not been released.
It’s basically “x.0 under development”.