Summertime is primetime for peaches, apricots, and nectarines, but there's always some confusion about what makes each of these three different types of stone fruit distinct. What is the difference between a peach and an apricot, anyway? Nectarines and peaches are pretty similar, too, and they are mostly interchangeable in recipes—so does that mean peach and apricot are the same fruit, too? This confusion isn't totally unwarranted, since peaches, apricots, and nectarines are all related. They're members of the genus Prunus, and as Harold McGee writes in On Food and Cooking, "They owe their name to the stone-hard 'shell' that surrounds a single large seed at their center."
But there are plenty of differences between peaches and apricots, despite the shared heritage. Peaches are generally larger than apricots; according to info from the US Department of Agriculture, a medium peach is about 2-inches in diameter while an apricot is about a quarter of the size. And yes, some apricots really do look like miniature peaches, fuzzy skin and all, but the taste of apricots is different than that of peaches. When ripe and fresh, apricots are both sweet and tart, while peaches are generally just sweet. Apricots also tend to be less juicy than peaches, meaning that you're less likely to get a face full of sticky juice after taking a bite.
Really, the difference between a peach and an apricot comes down to the fact that they are two different species of fruit. But even though peaches and apricots are different fruits, peaches and nectarines are technically from the same species—despite the fact that we often think of them as two totally different types of fruit. The main difference between a peach and a nectarine isn't the taste but the texture of the outer skin. The two fruits are basically genetically identical except for one gene that gives a peach a soft, fuzzy skin and keeps the nectarine sans fuzz. McGee adds that nectarines tend to be a little smaller than their peach brethren, but you can use them interchangeably in recipes.
No matter which stone fruit you choose to use, whether it's a peach or a nectarine or an apricot, you can't really go wrong with any of them, especially in the summertime.