Igneous rocks are rocks which form from cooling magma or lava. Magma Molten or partially molten rock material and dissolved gases. Magma is molten rock beneath Earth's surface. Lava Molten or partially molten rock material and dissolved gases. Lava is molten rock which has erupted at Earth's surface.
Texture is an umbrella term which includes different aspects of how rocks look.
Grain size is directly related to the conditions under which the rocks formed. Intrusive rocks cool slowly because they solidify inside the Earth. Extrusive rocks cool rapidly because they solidify at Earth's surface. Igneous rocks are also classified by their chemical compositions. Darker than felsic, lighter than mafic.