Outer Planets' are more distant from the Sun - they are Jupiter, Saturn, Uranus, Neptune and Pluto. They are called the 'Jovian planets' by astronomers because they are beyond Jupiter. Astrologically, Inner planets are considered 'personal planets' .Outer planets Jupiter and Saturn are 'social planets' while Uranus, Neptune and Pluto are considered 'transpersonal planets'. There are other bodies in the cosmos but these are the main models that are used in Astrology. The astrological chart shows the planets, and the Sun, in a circle around the earth .
Signs describe the way the planets express meaning.
They are like lenses through which the planets shine. There are 12 signs and they divide the 360 degrees of the circle of the zodiac into 12 equal divisions of 30 degrees each. So, planets are 'energies', signs are descriptive of how the energies express. When we say a planet is 'in' a sign, we mean it is in a particular position in the circle. This has nothing to do with the constellations that bear the same names as the signs.