As per OP's request, I am posting this as an answer.
Seeing as your question comes from a Pottermore article, let's look at the Pottermore articles for 'Alchemy' and 'Potions'.
Alchemy is "the search for the Philosopher's Stone"
Alchemy (the search for the Philosopher's Stone, which would turn base metal to gold and give the possessor eternal youth) was once believed to be possible and real. However, the central quest of alchemy may be more complex, and less materialistic, than it first appears.
One interpretation of the 'instructions' left by the alchemists is that they are symbolic of a spiritual journey, leading the alchemist from ignorance (base metal) to enlightenment (gold). There seems to have been a mystical element to the work the alchemist was engaged upon, which set it apart from chemistry (of which it was undoubtedly both an offshoot and forerunner).
The colours red and white are mentioned many times in old texts on alchemy. One interpretation is that they, like base metal and gold, represent two different sides of human nature, which must be reconciled. This was the inspiration for the Christian names of Rubeus (red) Hagrid and Albus (white) Dumbledore. These two men, both hugely important to Harry, seem to me to represent two sides of the ideal father figure he seeks; the former is warm, practical and wild, the latter impressive, intellectual, and somewhat detached.
Although there are books on alchemy in the library at Hogwarts, and I always imagined that it would be studied by very clever students in their sixth and seven years, Hermione most uncharacteristically ignores the opportunity. Perhaps she feels (as Harry and Ron certainly do) that, far from wishing to make another Philosopher's Stone, they would be happy never to see another one in their lives.
(Pottermore - Alchemy)
Potions mainly "duplicate the effects of spells and charms"
It is often asked whether a Muggle could create a magic potion, given a Potions book and the right ingredients. The answer, unfortunately, is no. There is always some element of wandwork necessary to make a potion (merely adding dead flies and asphodel to a pot hanging over a fire will give you nothing but nasty-tasting, not to mention poisonous, soup).
Some potions duplicate the effects of spells and charms, but a few (for instance, the Polyjuice Potion, and Felix Felicis) have effects impossible to achieve any other way. Generally speaking, witches and wizards favour whichever method they find easiest, or most satisfying, to produce their chosen end.
Potions are not for the impatient, but their effects are usually difficult to undo by any but another skilled potioneer. This branch of magic carries a certain mystique and therefore status. There is also the dark cachet of handling substances that are highly dangerous. The popular idea of a Potions expert within the wizarding community is of a brooding, slow-burning personality: Snape, in fact, conforms perfectly to the stereotype.
(Pottermore - Potions)