Pluto has no tail obviously, we are able to tell through the pictures we have of Pluto. Since Pluto is still around it cannot be a comet because it would have already died. Since Pluto does not fit the characteristics of a comet maybe it is an asteroid. An asteroid is a small irregularly shaped object. Since Pluto is larger than four hundred kilometers in diameter it maintains a spherical shape.
Asteroids have an airless rocky surface.
Pluto is rocky but on the center of the planet, water ice is on the surface of the planet. Perhaps Pluto is a satellite. A satellite orbits around another larger object. They have a great range of sizes and properties. Pluto does orbit around another larger object.