Weathering is the decomposition of rocks, soils and their minerals through direct contact with the Earth's atmosphere. Erosion is displacement of solids (soil, mud, rock and other particles) usually by the agents of currents such as, wind, water, or ice by downward or down-slope movement in response to gravity or by living organisms. Erosion occurs because of factors like wind, water, ice, human activities like deforestation etc. Weathering, on the other hand is caused by contact with the earth's atmosphere. These atmospheric conditions may be heat, pressure etc.
That's how they are different.