These have retained their hydrogen and helium atmospheres, but aren't massive enough for plate tectonics. They are generally smaller than 0.3 Earth masses.
These are massive enough to have retained a thick atmosphere which traps internal heat. The surface is scorching hot.
Too small to have retained their primary atmospheres. Generally smaller than 0.1 Earth masses.
These are massive enough to be considered Jovian worlds if they were in orbit around a star.
These are Planemo worlds most likely to be habitable. A thick atmosphere traps geothermal heat, allowing for liquid water oceans. The lack of solar heating means that the temperatures are similar all across the world.