I know that the #1 best strategy in parenting is modeling. If we want our LO's to say "please" and "thank you," then we're supposed to say "please" and "thank you." If we want them to say "I'm sorry," then we're supposed to say "I'm sorry." etc. But how do you handle it when the expectations for behavior are fundamentally different for you than they are for your LO, simply because of your respective roles? How do you explain this to your LO?
Recently, I had a talk with Charlie after he said some hurtful things about how he didn't love his little brother etc. (He's been experimenting with doing this lately -- telling each of us that he doesn't love us, that he doesn't like us, etc.) I told him "I don't like it when I hear you say those mean words. It makes me feel sad." Then, later on in the day, he was asking for a cookie for a snack, and I told him that he couldn't have one. Without missing a beat, he responded back to me "I don't like it when you say those mean words to me." I asked him what he meant, and he said "I don't like it when you tell me I can't have a cookie."

THEN, we had to have another talk about how my words weren't mean words, they were "teaching words," and I was allowed to say them because I was his mommy. But I really don't think he bought it.
How do you handle this? How do you, for example, teach your LO that sometimes when they ask for something from you, you're going to say "No," but that when you tell them to do something, they're not allowed to say "No." How do you explain that their requests are just requests, but your requests are sometimes orders?