How would you define each? I really do think I agree with you, as I've never done the deep immersion thing and rarely speak in-character. However, I always keep (or try to keep) my player/GM knowledge separate from my character knowledge and try to make my PC/NPC act and react in a realistic fashion.
For example, when I first joined the AD&D group I'm in now, my character was introduced into the campaign as a prisoner about to be sacrificed by gnolls. My guy was freed by one of the group's members, and told to wait (as he was wounded and weaponless) by a stairwell. He was not told that one of the group was magically disguised as the evil illusionist dude who had imprisoned him. It just so happened that the magically disguised PC came running down the stairs. Naturally, my guy reacted defensively when he saw the person he thought was his nemesis coming toward him.
But I didn't role-play this in the sense of talking in character and using thees and thous and mimicing my fighting stance or any such. It was more, "Ashar gets in his fighting stance and moves toward the illusionist."
Out of character, I knew that this was a party member, but there was no way my PC would have known. So I had the PC react in a manner consistent with that. But I wasn't really pretending to be Ashar, I was more just saying what he would have done.
Apologies for the length of the post, but is that kind of what you're thinking about?