How do consumers differentiate between complementary and substitute goods when making purchasing decisions?

Consumers differentiate between complementary and substitute goods based on how they are used together or in place of each other. Complementary goods are products that are used together, like peanut butter and jelly, while substitute goods are products that can be used interchangeably, like Coke and Pepsi. Consumers consider factors like price, quality, and personal preferences when deciding between complementary and substitute goods.