How would you describe the internal structure of the earth?
The internal structure of the earth is like a steel ball that has been inserted into the middle of a rubber ball that has then been rolled around in the mud which sticks to it.
The mud sticking unevenly on the outside of the ball represents the earth's crust. The rubber ball represents the mantle below the crust, and the steel ball inside is the earth's core. These are the basic layers.
Inside the earth, the mantle itself consists of an upper mantle and a lower mantel, and the iron consists of an outer core and inner core. The separations occur where the state of the substance changes. For the iron , the outer core is closer to a liquid, while the inner core is closer to a solid. Both are intensely hot.
If you need a 3-D representation of the internal structure of the earth, cut a spherically shaped avocado in half, and keep the half with the seed or pit. The pit is the core, the fruit is the mantel and the skin is the earth's crust. You can add in the other divisions as necessary.