Not sure if this is helpful, but that doesn't sound to me like just different words.
I use the word "see" because it's the best word to describe what is happening in my head. It's not literally seeing, but... it's very close, it's not just me remembering details about what something looks like, it's "visualizing".
I'm sorry, I don't know how to put into words the difference between the vision happening in my eyeball and the vision happening inside my head. There are differences, but they are very hard to articulate and there are fewer differences than there are similarities. The mental and eyeball "vision" are definitely at least running many of the same subroutines.
My feeling is that when someone says that they think words like "picture" or "see" are just social conventions, I suspect they're having a different experience than me. I would probably have settled on a phrase like "picture something in my head" even if no one else used that phrase, I can literally mentally trace out the outlines of the thing I'm imagining in the head. It's not just a list of attributes or descriptions, it's a thing that I am... again, for lack of a better word, "seeing", even though I'm not literally seeing it via my eyes in front of me.
What sticks out to me is that I literally can't think of any word that could be closer to what's happening then the words "vision", "seeing", "picture". Calling it a description is less accurate, it captures less of the experience than the word "seeing" does. Phrases like "replaying a scene in my mind", "remembering a sound", "an image popping into your head", etc... those are not rough poetic analogies, those are descriptions that are extremely close to what is literally going on inside my head.
> I don't have any visual experience at all. It doesn't even make sense to me
I am not going to try and diagnose anyone over the Internet, I'm not an expert on anything, but yeah, if you're curious about it that sounds to me a lot like aphantasia, at least as far as I understand aphantasia. You say the concept of comparing what's going on in your head to a picture doesn't make any sense at all to you? At that point I suspect it's not a difference in language; I'm not talking about being able to draw something or describe attributes about what it looks like, I'm talking about being able to... see it.
I don't know for certain, but I feel like picturing something in your head is (again, while not literally exactly the same as seeing something in real life) still not an analogy I would need to explain to someone who didn't have aphantasia.
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Articles like this are so fascinating to me, there are a couple of different parts of my experiences (ADHD, asexuality) that I always assumed were completely universal and then later in my life found out weren't. Whenever stuff like that happens to me it's always a surprising experience, and for some weird reason I'm always excited when I see it. Once you realize that certain things that you think are unique about you aren't, and that certain things that you think are universal aren't, and more than that you realize how easy it is to be in a situation where you'd never discover that -- for me it makes me feel like the world and the people around me are more interesting, and it makes me want to learn more about them.
At the end of the day it doesn't really matter if someone has aphantasia, it doesn't mean their life is going to get turned upside down. But I think sometimes it's just fun to learn about things and to think about how experiences shape people.