Difference between repository and pluginrepository

As @otakun85 stated, There is no technical difference at all. It's for having different configurations->behavior for plugins in contrary to normal artifacts. See repository vs. pluginRepository for more details.

Also check maven-users mailing list archives, It provides quite good explanation to it.

Maven will resolve plugin dependencies using the configured pluginRepository. Other artifact dependencies (eg. a parent pom) are resolved using repository. Note: Things available on maven central will be resolved by default so you wouldn't normally need to include repository for those.

For example, if your pom.xml specifies a parent pom and a plugin dependency that both exist in the same repository you must still specify both repository AND pluginRepository. If you only configure one then maven will complain with "Unresolvable X" errors.