What modifications did Kepler make to Copernicus model

Planets move in elliptical orbits and this theory was formulated by Johannes Kepler. Kepler's laws of planetary motion defined a set of rules followed by the planets while revolve around the sun and determines their orbits.

This modified the earlier theory of circular orbits from Nicholas Copernicus.

Actually, the answer on edge is:

Planetary orbits are elliptical.

Planets closer to the Sun move faster.