Whats the difference between Pepsi and Coca Cola? Don't they taste the same?

It’s kind of embarrassing to ask, but its a real question. I really can’t tell them apart. I hear people say “Pepsi is better” and another person say ” Coca Cola is better”. And sadly i’m the confused one and says ” Don’t they taste the same?”. So now, I want to know what is the difference between them.