What is the main difference between instrusive and extrusive igneous rocks?

Answer 1

One way to distinguish between intrusive and extrusive igneous rocks is to observe the crystal size.
Rocks formed below groung (intrusive) have must longer to cool, resulting in a larger crystal size.
On the other hand, rocks formed above ground (extrusive) have a much smaller crystal size

Answer 2

The MAIN difference between intrusive and extrusive igneous rocks is where they form. Although both are igneous rocks, the intrusive ones form below the Earth's surface, whereas the extrusive form above the surface. Intrusive Igneous cool much more slowly than extrusive Igneous. Hope that helps!

Answer 3

intrusive rocks form in the earths interior and extrusive rocks form outside (the earths surface)...in other words intrusive rocks form inside the earth and extrusive form on the surface...think of the IN part on IN trusive as inside..and the EX part of EXtrusive as outside..like in and out..hope its not to confusing!