Roleplaying is not the decision.
The PHB disagrees with you: "Roleplaying is... you as a player determining how your character thinks, acts, and talks."
Roleplaying is all the stuff that makes up the decision. If there is an orc and you decide to kill it because you want to swing and get exp for your fighter, that's roleplaying. If I want to kill the orc because my fighter is overcome by his hatred of orcs due to them killing my parents during a raid on my village, that's more roleplaying. We came to the same decision, but there was more roleplay involved with my decision.
No, there wasn't. There was a difference in
stance. The first decision was made in
author stance, in which a character's decisions and actions are determined according to the priorities of the player. The second decision was made in
actor stance, in which a character's decisions and actions are determined using the knowledge and perceptions of the character. There's no more role-playing involved in making decisions is actor stance than there is in making decisions in author stance.
Roleplaying is also in the descriptions. If you say, "My character tries to convince the lord to lend us aid.", you are roleplaying. If my PC says, "My lord, my party has aided you several times over the last year without asking for anything in return. We saved your daughter at great peril. We drove away bandits that were preying on your merchants. Right now we are in dire straights and need to borrow the Chalice of Warning for just one week.", that involves a lot more roleplaying.
No, it doesn't. It involves "in-character" versus "out-of-character" roleplaying. Speaking in the first-person doesn't yield more role-play than speaking in the third-person.
Roleplaying is not all or nothing. You are engaging in a False Dichotomy.
No, I'm not. A dichotomy would involve two categories, role-playing and not role-playing. I don't think I've said anything about not role-playing because, in the context of actually
playing an RPG, such a thing doesn't really exist. What it would look like is a player sitting at the table and saying, "I don't know what my character thinks, does, or says." At that point, you're just not playing the game!
But assuming the two categories are role-playing and not role-playing, how is that dichotomy false? What other category is there, or how is role-playing sometimes not role-playing?