* Elements are pure substances made up of only one type of atom. Examples include oxygen (O), hydrogen (H), and carbon (C).

* Compounds are formed when two or more different elements combine chemically in a fixed ratio.

Ammonia (NH₃) is made up of nitrogen (N) and hydrogen (H) atoms combined in a ratio of 1:3. This means that it's not a single element, but a combination of two, making it a compound.