Biome Kingdom is an mod that adds an biome into your world called tropical rainforest it is an rare biome that is not easy to find and it blends in with the jungle biomes perfectly as it looks very similar and the only way to differentiate an tropical rainforest and an jungle biome in game is that the trees in an tropical rainforest are much taller and the grass has a more green tropical look. So yes it is basically an upgraded jungle biome so there is not too much in this mod. 
