What's the difference between a molecule and a particle

I had this question.

What is the difference between a molecule and a particle?

Let's see an approach from small to big and then to clarifies, will do the inverse with a concrete example.

Many are familiar with the atoms. So, the atoms are made of particles, which are electron, proton and neutron.

Then, many atoms made molecules.

So far the main question is solved. But when I was looking for the answer I found something very interesting. How atoms stick together, and how new elements are created because of this 'stickness'.

The way they get together depends of the type of substance. Each substance have a different kind of atoms. The very basic one is one of the most common in the universe which is the Hydrogen. This atom only have one particle.

Now let's visualise the atom to put it clear. The center of the atom and let's create concentric circles around it. Each of this circles can hold a maximum amount of particles around it. The hydrogen have the center and just one electron in the first shell. The maximum amount that shell one can hold is 8, so he is looking for other substance to complement the structure and at least in the shell one. The oxygen have 6 electrons in shell one. So, one particle of oxygen will need two particles of hydrogen to create this H ² O, water !

The images will illustrate better this. You can look more information about this, is awesome, but this was just a glimpse of the complex world of this small world that all we are made of.