* Substances are made up of only one type of molecule. For example, pure water is H2O, and pure sugar is a complex carbohydrate.

* Mixtures are combinations of two or more substances where each substance retains its own properties. When you mix sugar and water, the sugar molecules are surrounded by water molecules, but they don't chemically change. You can still separate the sugar and water by evaporation or other methods.

Let me know if you'd like more examples!