Peertube is really just an "app" providing a simple way to host and publish your content online outside the control of "service" providers that can also easily be accessed and shared by the "fediverse" (in this case activitypub supporting federated networks of servers and end users).

You can consume peertube content with any activitypub client that supports its types. In short, peertube is an accessible way for users to publish their videos to activitypub.