For context you might be already familiar with meta and Zuckerburg's aim towards metaverse which he defines as the next social platform where people will hangout or carry out office related tasks in the upcoming years. Metaverse in itself is not a place but is a platform that holds or host different worlds virtually which individuals can join through VR Headsets from companies like Oculus, Meta owned corporation that specializes in VR category equipment.
Not so back apple also launched it's VR Headset which it named 'Vision Pro'. So as already stated above metaverse is not itself a world but a platform that holds different set of world among which one of the them is Horizon Worlds or more heard like Meta Horizon Worlds, a place to hangout with your friends virtually as floating avatars.
Facebook or better Meta launched Horizon Worlds back in 2020 as a beta platform for virtual explorers, The aim was same to allow users to develop virtual experiences by using precise set of tools provided by Meta.