Plutonic rocks are igneous rocks formed deep beneath the Earth's crust. The rocks have a coarse grain size. These rocks can be sorted even further based on their chemical composition. They can be spread into acidic, basic or ultrabasic types.
Subvolcanic Rocks
Subvolvanic rocks are formed in the mid to shallow areas of the Earth's crust. Also known as hypabyssal rock this form of intrusive igneous rock. The rocks formed here have medium grain size.
Volcanic Rocks
Volcanic rocks are very similar to plutonic rocks because they can be separated into the same groups. Volcanic rocks are formed close to the Earth's surface and are fine grained rocks.
Other Igneous Rocks
Other igneous rocks are any igneous rock that doesn't fall directly into one of the above categories. Any rock not in the above category is just classified in its own category.