If two things are basically the same, you can say that they're the equivalent of each other. Like, studying advanced physics is the equivalent of banging your head against the wall.
Equivalent's Latin roots are "equal" and "value," which suggests that the word originally was used to describe things that had the same value. Now it can be used to describe things that have the same effect, or importance, or role — for example, "England's Parliament is the equivalent of America's Congress." It can also be used as an adjective: "Eating a bowl of Sugar Pops for breakfast is equivalent to starting your day with two scoops of ice-cream."