Both ash and pumice are made up of volcanic rock fragments. Here's a breakdown:

* Ash: Ash is made up of very fine particles of volcanic rock and glass, less than 2 millimeters in diameter. It's essentially pulverized rock, often created by the explosive eruption of a volcano.

* Pumice: Pumice is a type of volcanic rock that's full of air pockets, giving it a very porous and lightweight texture. It's formed when frothy lava cools quickly, trapping gas bubbles.

So, the material itself is similar, but the difference lies in the size and composition of the fragments:

* Ash: Tiny, pulverized rock fragments.

* Pumice: Larger, porous rock with gas bubbles trapped within.