In French the translation is the same but I wonder why in English you have two words for this ? I think that's because there is a slight difference between these two words but I don't get what it is !
I feel the need to observe that the answer to any question of the gist "Why does English have [more than one] word for this?" is "Because the English is what happens when a whole language becomes a compulsive hoarder."– CodeswitcherMay 21, 2014 at 22:49
I said that but there are also lot of examples where in French we have many word when you have one. Perhaps the most popular example is "tu" and "vous" in French replaced by "you" in English.– KoObOMay 21, 2014 at 23:39
You now find a lot of people using admixture as a synonym of mixture; it is so widespread that this cannot be regarded as an error.
But the classic use of admixture is narrower: the prefix ad- (Latin = “to, toward”) implies that a new component or ingredient is brought “to” an original substance and mixed “into” it. We might for instance speak of the classic Manhattan cocktail as
rye whiskey with an admixture of vermouth and bitters.