Is sour milk the same as buttermilk?

Sour milk and buttermilk are not the same, although they can be similar in taste. Sour milk refers to milk that has naturally fermented, resulting in a tangy flavor due to lactic acid bacteria. Buttermilk, traditionally, is the liquid left after churning cream into butter, but it is often also produced by adding cultures to low-fat milk. Both can be used in recipes, but their production processes and characteristics differ.