Both are geological processes. Erosion is the displacement of rock particles or soil from one place to another on the surface of earth with the help of agents like air and water whereas natural weathering is has a direct contact with the surface of earth and the atmosphere. Natural weather usually decomposes the minerals or rocks which are present on the surface of earth. So we can say that weather is decomposition of rocks at their own place while erosion takes place by the help of air or water.