Yup, the Sun is a star because it can sustain and produce its own energy through nuclear fusion (or the process of binding two hydrogen nucleis to become helium, which also emits large quantities of energy)
The Pluto is what we call a proto-planet or Neptunian planet. Pluto is not a meteor. Eventhough Pluto isn't a planet, Pluto has managed to accomplish two out of three requirements. One is that Pluto is quite big (about 3000 km in radius) and is spherical in shape, which are the two out of three criteria for an object to become a planet. The third requirement was that a planet should clear its orbit, like Earth or Jupiter or Mars does. Unfortunately for Pluto, there are a lot of objects buzzing around Pluto's orbit, which fails it on the requirement to become a planet.
