Sunspots are the dark patches seen on the visible surface of the Sun. Sunspots are caused by a strong magnetic filed which blocks the outward flow of heat and energy from the core to the photo sphere. Sunspots are relatively cooler regions on the Sun's surface, but they still have a temperature of about 4000*C.
Sun flares are the violent eruptions on the surface of the Sun. Huge quantities of heat and energy are released in these eruptions. They are caused by the collapse of magnetic filed around the sunspots. At times, the gigantic flame may shoot up to a height of 1,00,000 kilometers. Such flames are known as 'Solar prominence'.