The Earth's surface temperature is largely determined by the amount of energy it receives from the Sun and how much of that energy is reflected back into the cosmos. Weather system circulate that energy in the atmosphere.
Heat within the Earth is the result of two main processes, residual heat from planetary accretion and heat from radioactive decay. The main decay elements are potassium-40, uranium-238, uranium-235, and thorium-232 . The temperature of the Earth increases with depth. For most of the Earth, the geothermal gradient (the rate at which temperature increases) particularly in the crust, is $25$ $^oC$ per km.
In subduction zones, where one tectonic plate goes under another tectonic plate (two plates converge), localized heating occurs due to friction between the plates. Subduction zones are locations with high rates of volcanism, earthquakes and mountain building; as occurs in New Zealand.
Geological hotspots are volcanic locations where it is thought the mantle is anomalously hot compared to the surrounding mantle. They occur on or near plate boundaries, or far away from them. Hawaii is a hotspot away from a plate boundary and in the middle of the largest ocean on Earth. Yellowstone is a hotspot on land, near the plate boundaries along the west coast of North America. Iceland is thought to be a hot spot on a diverging plate boundary in the middle of the Atlantic Arctic region.
The Volcanism of Earth has nothing to do with the surface temperature of the planet, it's all about geological processes where molten rock is forced to the surface of the planet under pressure.
Additionally, volcanism isn't confined to the Earth. Mars was once volcanic, Venus still is, as is the Jovian moon Io, the Saturnine moon Enceladus and the Neptunian moon Triton. These are examples of volcanism within our solar system. Except for Venus, all the other locations of volcanism in the solar system have very cold surface temperatures.
Magma erupts onto the surface from vents on the floor of paterae or on the plains from fissures, producing inflated, compound lava flows similar to those seen at Kilauea in Hawaii
Whereas, Enceladus and Triton experience cryovolcanism, where ice and water are ejected under pressure.