Click to read in-depth answer. Keeping this in consideration, what is a sponge server?
Sponge is a server mod used on 1.8 and above modded servers wanting to use plugins. Sponge requires the use of a different type of plugin, known as a Sponge plugin. So by that logic, Bukkit/Spigot plugins cannot be installed on a Sponge server.
Subsequently, question is, what does Sponge Forge do? SpongeForge, a coremod for Minecraft Forge, which is an existing Minecraft: Java Edition modding framework famous for spurring the Minecraft modding scene. Forge lacks a cross-version API, and this is where Sponge steps in. Sponge allows server owners to deploy Sponge plugins with ease, making server management easier.
Subsequently, one may also ask, how do you make a sponge server?
Installing Forge via GUI
Do spigot plugins work with sponge?
bukkit/spigot plugins won't work on Sponge. However some (very very few) plugins are universal and they may work on both platforms.