Anchovies are no sardines

Anchovies and sardines are both small, silvery, oily fish, and they are even related. Nevertheless, they are different fish, and connoisseurs will even be able to pick out the "true" sardine or anchovy from among the rest.
Anchovies (Engraulidae) and herrings and sardines (Clupeidae) are fish families that both belong to the order Clupeiformes. Most fish in this order are silvery with stream-lined, spindle-shaped bodies, live in large shoals and eat plankton that they filter from the water with their gill rakes.
Anchovies are found in the Atlantic, Indian and Pacific oceans, and some species enter or live in freshwater. They have translucent bodies with a silvery stripe down the flanks, and most species are less than 6 inches long.