Dupe

The comparison almost always starts with the ingredient list, because it is the only part of a formula anybody publishes. Two lists look alike, the price differs tenfold, and the conclusion writes itself. That is a reasonable place to start and a poor place to stop.

A list is an order, not a recipe. Ingredients are ranked by how much of each is present only down to a small threshold; below it a maker may list what remains in whatever order it likes. So the top of a list is informative and the tail is a presence check — this is in here, somewhere, in some amount.

What no list carries: the grade and purity of a material, the size of a particle, the pH the whole thing settles at, whether something unstable was protected or merely added, and the vehicle that decides how much of it gets past the surface at all. Two products with the same list can behave differently. Two with different lists can behave the same.

Which makes the useful question a different one. Not are these the same, but does this do the job on my skin at a price I will actually repurchase — a dupe used every night beats an original saved for special occasions. One caveat: where a claim rests on a measured figure, sun protection above all, that figure belongs to the product that was tested. A copy inherits none of it.