WTF McDonalds?

So apparently The ONLY difference Between a Double cheeseburger and a McDouble is ONE slice of cheese and .89 cents? When I went up to the counter to inquire about what was the difference between the 2 sandwiches, every employee ignored me before I asked the counter girl about the discrepancy, she barely acknowledged that I spoke to her and turned to get the manager. I politely asked what the difference was, she never answered me but instead just took my sandwiches and ordered a recook. When she handed me back the 2 burgers, I opened them and they looked the same again. So I asked her (politely) what is the difference between the 2? She answered me politely that the only difference was placement of cheese or something that, I’m still not sure what the answer is... however, had she just explained this to me when I originally went to ask (instead of walking away and taking my sandwiches without a word), I would’ve had my meal and been on my way... So because of the lack of communication, I was HIGHLY DISSATISFIED with my experience at McDonalds today.