Inspired by a recent exchange here: a brief breakdown of different ways to look at “what are perfumes made of?”
On a really supernerd level, the answer is “atoms, DUH”, but let’s start from a more useful point. Molecules. Since all matter is chemicals, so are perfumes. These molecules are what the compounds are made of – compounds of both natural and synthetic origin (and some of the synthetics are nature-identical, e.g. if the perfume contains synthetic geraniol, it’s molecularly identical* to the geraniol that roses produce in nature).

Natural raw materials are complex chemical substances, and the result of them ending up in perfume is an example of a lot of human labour and ingenuity.
Ingredients: bergamot oil, rose absolute, iso E super, muscenone delta, ambroxan, patchouli oil, vanillin, ethyl maltol, cedarwood oil, benzoin…
These all come from somewhere - first, the naturals have a plant species & variant + a growing region (e.g. Turkey or Italy) + a method of extraction (distillation vs solvent extraction vs Co2 extraction etc). These factors determine the chemical properties (and thus, the smell and usefulness) of natural materials.
Synthetic materials may be manufactured by a number of companies - this is where that little asterisk* came from for the nature-identical; geraniol made by one company may be very slightly different if made by another, due to the production methods used. Not enough of a difference to matter, but for the sake of accuracy let’s acknowledge it.
An accord is another way of saying “a harmonious co-existence of ingredients in a blend that creates a new smell which feels greater than the sum of its parts”. For example patchouli and vanillin will start to smell like chocolate. And now a brand could say “this perfume smells like chocolate. Let’s list chocolate as a note.”
Notes lists are NOT ingredient lists. They are not even necessarily a representation of provenance of the natural items listed. Sometimes the actual ingredients in the perfume overlap what the notes list says. Sometimes they don’t. Notes lists are a brand’s way of describing what they want or hope you will smell.