Here's a breakdown:

Similarities:

* Many minerals are common to both: Both igneous and metamorphic rocks are formed from pre-existing minerals. So, many of the same minerals, like quartz, feldspar, mica, and hornblende, can appear in both rock types.

* Same elements: The basic building blocks, the elements, are the same in both types of rocks. They just get rearranged and combined in different ways.

Differences:

* New minerals can form: Metamorphism involves heat and pressure, which can cause existing minerals to recrystallize or even transform into entirely new minerals that are more stable under those conditions. These are called "index minerals" and can be used to determine the conditions under which the rock was metamorphosed. Examples include garnet, kyanite, and staurolite.

* Mineral proportions can change: Even if the same minerals are present, their proportions can change dramatically during metamorphism. This can affect the overall appearance and properties of the rock. For example, a granite (igneous) might become a gneiss (metamorphic) due to the realignment of minerals under pressure.

* Texture differences: The arrangement of minerals within a metamorphic rock is often distinctive. For example, foliation (a layered texture) is common in metamorphic rocks and is rarely seen in igneous rocks.

In summary:

While igneous and metamorphic rocks often share many of the same minerals, metamorphism can introduce new mineral types and significantly alter the proportions and arrangement of existing minerals. This makes metamorphic rocks unique and often allows us to learn about the conditions of their formation.