The prevailing condition causing the difference between the two formation zones is that of temperature.
The inner planets, or terrestrial planets, were formed by accretion. Accretion is an accumulation of smaller rocky materials colliding with each other, sticking to each other, and forming an evolving larger mass. The inner planets were too close to the sun to be formed from ice and methane, which is the primary constituency of the outer planets. So they formed by small particles bombarding each other, sticking to each other, and building a protoplanet with a rocky exterior.
The outer planets, or Jovian planets, contrastingly, were past the hot zone that bound the inner planets to rocky, solid materials. The outer planets are composed primarily of a collection of gasses, namely methane, water (ice), hydrogen, and helium. These planets were cold enough to accumulate large quantities of gaseous materials, with a low percentage of heavy materials.
The inner planets, in order, are Mercury, Venus, Earth, and Mars. Jupiter is the largest and first Jovian planet, followed by Saturn, Neptune, and Uranus.