There are so many different elements out there each made up of their own special little atoms. But just like the cells of our body, such as White Blood Cells, Red Blood Cells, Liver / Kidney / Intestinal Cells, looks can be different but each cell is made up of the same organelles (eg nucleus, mitochondria, vacuoles).
Look also at food labels! Notice how all food actually more or less made up of 3 big type of food substance!
Curiously enough, all atoms are made of 3 subatomic particles.
The exciting difference that differentiates between an element like say Hydrogen from Copper lies in the the number of subatomic particles of the atoms of each element.
Appearance can be deceiving. Hydrogen on its own is an invisible gas! But Copper is a nice reddish brown metal.
And yet all the differences lies in the number of protons, electrons and neutrons that make up any atom!
Learning point: All atoms are made up of protons, electrons and neutrons
learn about Protons, Electrons and Neutrons