What is the difference of obsidian and bed rock

Obsidian is a volcanic glass. It is produced when magma from volcanoes is cooled and solidifies rapidly, before there is time for crystals to grow. It is usually black in color. It shatters like glass and makes excellent axe and arrow heads and the main mineral in it is quartz (silica).

Bedrock is the solid rock that lies underneath the soil in broken, weathered rock. It is not found beneath anything in particular, it simply lies below the loose weathered material on the surface. Bedrock may be many different types of rock that extend for kilometers down into the earth's crust.