Umm... I think @ernest might be able to give most accurate reply?
Different Fedi server types can present the same ActivityPub actions in different ways. What appears to be an upvote on Kbin might be a boost on Mastodon, but they would be the same action within the ActivityPub protocol (which is the technical standard servers use to communicate to each other on the Fediverse).
There's a similar thing on PeerTube where an account's channels on PT are presented as groups on Mastodon.