The comets from Oort Cloud help us to sample-material formed far away from the sun, while the short-period comets from Kuiper Belt sample-material are planet-simals in solar nebula disk but do not form planets. Exploring the Kuiper Belt will also affect our understanding of the early evolution of planetary systems.
Objects in the Oort Cloud and the Kuiper Belt have different histories and can therefore have different compositions. Therefore, astronomers are keen to compare detailed measurements of comets derived from these 2 regions of source. Most of the bright comets studied in the past (Halley, Hyakutake, HaleBopp) are Oort cloud comets, but P67 & some other comets target-ed for spacecraft measurements over the next decade are comets of the Jupiter family from Kuiper belt.
The Kuiper belt is made from ice-and rock planetesimals, a remnant of the constructing blocks of the planets. Since it is gravitationally related to Neptune, it can help us understand the formation and history of the solar system. As the giant planets formed, their gravity profoundly affected the orbits of objects in the Kuiper Belt. Computer simulations of the early evolution of the planetary system suggest that the gravitational interactions b/w giant planets & the remaining planetesimals caused the orbit of Jupiter to drift-inward, while the orbits of Saturn, Uranus, & Neptune expanded, taking the Kuiper Belt with them.
Another hypothes is relates to a fifth giant planet that was completely ejected from the solar system when the planetary orbits shift. Neptune’s retrograde (reverse orbit) moon Triton (which is almost the size of Pluto) may have been a Kuiper Belt object captured by Neptune during the orbits shift. It seems clear that the Kuiper Belt could contain important clues as to how our solar system achieved its current planetary configuration.