We're all part of the Fediverse which includes Masto, Pixel, PieFed, Lemmy etc all communicating on the same interoperable ActivityPub protocol

Under that is the "Lemmy-verse/Thrediverse" that is what would be "link aggregator" type social media (eg reddit) and includes PieFed, Lemmy, MBin etc.

While very cool in that it basically ruins the whole notion of centralized Social media, it has its quirks. Like what this meme is about, there's no perfect way to translate a Lemmy reply to a mastodon user or a masto reply to a Lemmy post for a Lemmy user