How many versions of Sponge are there!?

I see people talking about SpongeVanilla then SpongeForge… Im confused, how many different types of sponge are there!? If theres SpongeVanilla and SpongeForge, is there SpongePlugin???

Also how do i download sponge

Most all of this can be answered here: https://docs.spongepowered.org/master/en/server/getting-started/implementations/index.html