Kepler’s three laws are applicable to the motion of planets in the solar system. Newton’s laws of motion, on the other hand, describe all manner of movements.
Building on Kepler’s work, Newton did turn his focus to planetary movement. For example, where Kepler showed the connection between an orbit’s period and its radius, Newton expanded this to show that the connection is dependent on the system’s mass and that it should apply to all objects that orbit one another under gravity’s influence.
In addition, Kepler could describe how planets moved, but he couldn’t accurately explain the why behind his laws, Newton provided a much fuller explanation and explained gravity.