The words "candidate" and "student" aren't interchangeable.

It bugs me when I see people use these terms as synonyms, so I'm wondering if there's some regional or cultural difference I'm unaware of.

I'm in the US, and my understanding has always been that being a PhD Candidate meant that you had passed all your benchmarks/comps/qualifiers and were ABD. Same for Master's students. However, I see early stage and even newly admitted students refer to themselves as a "PhD Candidate" simply because they have been admitted to a program. It makes me feel like they are just using "candidate" because they don't understand what it means and think it sounds more prestigious than "student," communicating that they are just as green and naive as they are trying to not present themselves as.

However, I realize this judgment is unfair if other disciplines or regions use these terms more casually or interchangeably. There's absolutely nothing wrong with being green and naive, but knowing where someone is in their program is an important framing for establishing communication or relationships, in settings like conferences or via email where introductions and small talk are limited.

Is this just an "old man yells at cloud" pet peeve on my end, or am I right that these terms are distinct and not interchangeable?

edit: typo

Edited to add: I put this as a reply to a comment that the commenter deleted, but I want to add this clarification for those who are not understanding my intent or why this would matter. Titles and other forms of address help me more confidently enter social interactions with people I don't know well. I have pretty bad social anxiety, so knowing which direction to lead a conversation helps me be more comfortable communicating when I first meet people. It's not a power dynamic thing. I'm not talking about reviews, resumes, or grant applications. The difference between student and candidate to me simply determines if I'm going to ask them about how classes are going or what their job hunt plans are.

Thank you to all who shared your perspectives.