Dark vs milk chocolate

Milk solids. That single addition changes the bitterness, the melting behaviour, the working properties and how much of the bean you can taste.

Side by side

	Dark	Milk	Why it matters
Composition	Cocoa solids, cocoa butter, sugar.	The same, plus milk solids.	Milk proteins bind tannins and coat the palate, which suppresses bitterness and astringency. That is the mechanism behind every other difference here.
How much of the bean you taste	A great deal. Origin character is audible.	Considerably less. Dairy and caramel notes dominate.	It is why almost all single-origin and bean-to-bar production is dark, and why milk chocolate is generally made from bulk-grade beans deliberately rather than as a compromise.
Working temperature	Melts to about 50°C safely; tempers at 31–32°C.	Scorches above about 45°C; tempers at 30–31°C.	Milk chocolate is less forgiving of heat, because milk solids burn before cocoa solids do.
Ganache ratio	About 2 parts chocolate to 1 part cream for a firm set.	About 3 parts to 1 for the same firmness.	Using the dark ratio with milk chocolate produces a ganache that will not set.
Sugar	Roughly 30% of a 70% bar.	Typically 45–50% once milk solids are accounted for.	The percentage figures are not comparable between the two, because what makes up the remainder differs.

Choose Dark when

When the point is to taste the chocolate itself, when pairing with anything bitter or tannic, and in most baking where the recipe supplies its own sugar.

Choose Milk when

When pairing with coffee or nuts, when the audience includes people who find dark chocolate harsh, and when a softer, sweeter result is wanted.

Compared in

Dark chocolateSet against Milk, with the practical consequence of each difference.
Milk chocolateSet against Dark, with the practical consequence of each difference.

Covered in

Dark chocolate explainedThe side-by-side with milk chocolate.

Sources

ChocolateHQ editorial synthesis — ChocolateHQ(citation identity confirmed; passage not re-read)