Protoplanet vs. Planet

Difference Between Protoplanet and Planet
Protoplanetnoun
An astronomical object, approximately the size of the Moon, formed from the mutual gravitational attraction of planetesimals; they are thought to collide with each other and slowly form planets
Planetnoun
Each of the seven major bodies which move relative to the fixed stars in the night sky—the Moon, Mercury, Venus, the Sun, Mars, Jupiter and Saturn.
Planetnoun
(astronomy) A body which orbits the Sun directly and is massive enough to be in hydrostatic equilibrium (effectively meaning a spheroid) and to dominate its orbit; specifically, the eight major bodies of Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. (Pluto was considered a planet until 2006 and has now been reclassified as a dwarf planet.)
Planetnoun
A large body which directly orbits any star (or star cluster) but which has not attained nuclear fusion.
Planetnoun
In phrases such as the planet, this planet, sometimes refers to the Earth.
Planetnoun
any of the celestial bodies (other than comets or satellites) that revolve around the sun in the solar system
Planetnoun
a person who follows or serves another