I agree that those two statements can elicit different responses. I try to take the latter statement even closer to expressing myself. Instead of saying "I believe what you did is rude" I'll try to say "When you did that thing, I felt angry or if I'm more honest, sad."

I wrote a post on this back in the day calling it the subjective adjective, basically that when we use adjectives, often it carries an objective nature to it, aka "everyone believes this is the description" and even if you were to say to me "I believe what you did was rude" I may lock in on "rude" and forget it was your perspective. I may even ignore your emphasis on what I did and put it who I am. "This person is calling me rude!" Even though you weren't.

So I try as much as I can, especially in conflict scenarios, to avoid using adjectives about them or their actions and more so to use adverbs (I think?) about how I'm feeling.

"You're rude" to "I believe what you did is rude" to "I felt hurt when you did that."