* Atom: The smallest unit of an element that retains the chemical properties of that element. It's like a building block.

* Element: A pure substance made up of only one type of atom. It's like the entire structure built from those blocks.

The commonality:

* Atoms are the fundamental building blocks of elements. Think of it like this: You can't have a hydrogen element without hydrogen atoms, just like you can't have a house without bricks.

In simpler terms:

* An element is the *type* of atom (like "hydrogen")

* An atom is the *individual unit* of that element (like a single hydrogen atom)

Let me know if you'd like more detail!