Some people find it confusing what is meant by plot and meta, so in this article we will go over the differences.
Plot is anything that can be considered a story or part of the roleplay. It is not something done in the usual Minecraft survival world (such as building a base) but instead usually to do with the politics on the server.
Meta is anything that is, as described by the dictionary, (of a creative work) referring to itself or to the conventions of its genre; self-referential. An easy way of thinking about it is that if it's not part of the story but also not a generic Minecraft routine, then it is part of the meta. Meta can still be referenced in the plot, which is referred to as 'breaking the fourth wall'.
General is anything that doesn't fit into either of the above categories, meaning something just a part of Minecraft such as homes.