In English: Atoms, elements, compounds, substances...

It's a mess.
In the Encyclopedia britannica (https://www.britannica.com/science/chemical-compound), I looked for the definition of "chemical compound", and I found a very messy and wrong text.
Indeed, here it is: "chemical compound, any substance composed of identical molecules consisting of atoms of two or more chemical elements".

And immediately, you see the mistake, as a "substance" is a material object: water is a liquid substance, in the ambiant conditions, and iron is a solid substance, with metallic aspect. But water (the substance) is made of identical objects, i.e., molecules ("water molecules"), which are made of atoms of different kinds, such as hydrogen (the element, not to be confused with dihydrogen) or oxygen. And "water" is also the name of the compound "water", i.e. the chemical category of all molecules made of one oxygen atom and two hydrogen atoms.

For sure, the fact that "water" applies to a substance  and a compound creates confusion. Moreover, the word "water" applies to the chemical pure water (substance) as any tap water, or water in the river, or sea water, which are rather aqueous solutions containing a lot of solutes, such as ions, molecules, etc.

Let's read more: "All the matter in the universe is composed of the atoms of more than 100 different chemical elements, which are found both in pure form and combined in chemical compounds."
Yes, no, the matter of the universe is not composed of the atoms of etc."... because there are a lot of subatomic particles, not considering dark matter.

More : " A sample of any given pure element is composed only of the atoms characteristic of that element, and the atoms of each element are unique". No, again : a "pure element" does not exist : an element is an element, a category of atoms, and the question of purity has no meaning here. Purity can only apply to substances, to materials.
And no again, the atoms of an element are not all the same, because some can have more neutrons than others. Wrong again: don't you think it's too much?

More :
"For example, the atoms that constitute carbon are different from those that make up iron, which are in turn different from those of gold." : here, the mistake in the "make up". Stricto sensu, objects don't "make up" a category.

" Every element is designated by a unique symbol consisting of one, two, or three letters arising from either the current element name or its original (often Latin) name." : yes.

"For example, the symbols for carbon, hydrogen, and oxygen are simply C, H, and O, respectively. The symbol for iron is Fe, from its original Latin name ferrum.  : yes.

" The fundamental principle of the science of chemistry is that the atoms of different elements can combine with one another to form chemical compounds." : here, there is a pleonasm, was chemistry being a science, expressions such as "the science of chemistry" is too much.

And here, I have enough, but shouldn't EB make corrections?