Minecraft Plugins vs Mods
The difference between plugins and mods, and how to choose the right server type.
Plugins (Paper Servers)
Plugins run only on the server. Players connect with the vanilla client - no downloads required.
Plugins use the Bukkit/Spigot API. Common examples: EssentialsX, LuckPerms, WorldEdit, Vault.
Install plugins via the GameGrid Mods tab, whose marketplace search is scoped to Bukkit plugins for a Paper server, or upload .jar files to the "plugins" folder via the Files tab. Restart afterwards - plugins are read at startup.
Each plugin has its own config folder inside "plugins/<pluginname>/". Edit configs with the server stopped.
Mods (Fabric/Forge/NeoForge Servers)
Most mods run on both the server and the client, and where they do, every player must install the same mod at the same version to connect. Some mods are server-side only and players need nothing - the mod's own page says which.
Install server-side mods via the GameGrid Mods tab, or upload .jar files to the "mods" folder via the File Manager.
Players install the matching client mods in their own Minecraft client "mods" folder.
Modpacks bundle many mods together. Server-side, just drop all the mod .jar files in the "mods" folder.
Most Fabric mods require the Fabric API mod, installed into mods/ like any other mod. Forge and NeoForge do not have a single equivalent, but individual mods often depend on library mods such as GeckoLib or Cloth Config - install everything the mod's page lists.
Mods are tied to the loader they were built for. A Fabric mod will not load on Forge or NeoForge, and a Forge or NeoForge mod will not load on Fabric. They are all .jar files in a folder called mods/, so nothing stops you putting the wrong one there - check the loader label on the mod's download page.
Which Should You Choose?
Want minigames, economy, land protection, and players join with vanilla client? Use Paper + plugins.
Want new content (items, blocks, dimensions, mechanics) that players must install? Use Fabric, Forge, or NeoForge + mods.
You cannot mix plugins and mods on the same server. Paper does not run mods. Fabric, Forge, and NeoForge do not run Bukkit plugins.
For modern modded servers, NeoForge is the standard - most actively-maintained Forge-ecosystem mods target it. Use legacy Forge for older packs that were never ported.
Installing a modpack? Use the loader the pack names, not the one you would have picked.
For a fuller comparison of all five types, see Choosing a Minecraft Server Type.