Читая Стейнбека, наткнулся на следующий фрагмент.
"Got any coke?" another character asked. "No," said the proprietor. "Few bottles of Pepsi-Cola. Haven't had any coke for a month. … It's the same stuff. You can't tell them apart" (Wayward Bus, by John Steinbeck).
A вообще, они отличаются чем-нибудь друг от друга?