Magma vs. Lava: The Key Distinction
The only difference between magma and lava is their location. Magma is molten rock that is stored beneath the Earth's surface. When this molten rock erupts and reaches the surface, it is then called lava.
An Example of the Transformation
Think of a volcano. The vast chamber of molten rock deep inside the volcano is filled with magma. During an eruption, as that molten rock flows out of the volcano's vent and onto the land, it is reclassified as lava. Once the lava cools, it hardens into igneous rock.