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Oort cloud vs. Kuiper belt

Oort cloud

[awrt kloud, ohrt] / ˈɔrt ˌklaʊd, oʊrt /

noun

Astronomy.

a region of our solar system far beyond the orbit of Pluto, in which billions of comets move in nearly circular orbits unless one is pulled into a highly eccentric elliptical orbit by a passing star.

Kuiper belt

[kahy-per belt] / ˈkaɪ pər ˌbɛlt /

noun

Astronomy.

a disk-shaped region on the edge of the solar system that contains masses of ice and icy rock, believed to be the source of comets with orbital periods of less than 200 years.