The Pickensverse is the theorized multiverse relating to Jim Pickens, a prominent character on the channel. Often times, Jim's lore and backstories can contradict each other, leading fans to create the "Pickensverse" theory in order for the multiple versions of Jim to coexist. The Pickensverse is part of the Kevinverse. However, the terms cannot be used interchangeably, because the Pickensverse relates specifically to Jim Pickens and his antics while the Kevinverse relates to the channel as a whole.
Because the Pickensverse is non-canonical, it is not the only explanation for Jim's conflicting lore. See the Jim Pickens Timeline for a running timeline of Jim's life.