or
It is pretty clearly indicated in the first sentence of each repo :
ARKit-Plugin : This is a native plugin that enables using all the functionality of the ARKit SDK simply within your Unity projects for iOS.
or
ARInterface : Experimental cross-platform framework for mobile AR […].
ARInterface does include an outdated version of ARKit, but it adds a high-level layer of cross-platform functionalities that can easily be used with both the latest versions of ARKit and ARCore. Keep in mind that it is still experimental.