tl;dr Neckwear tag use confusion because in theory they refer to the same concept just at different sizes but in practice they aren't.
I started thinking about this when I was replacing heart collar mistags that were meant to be heart necklace and this got me a bit curious and confused about the way we use choker and collar, though more specifically collar than anything else.
As I see it now, I've generally understood that chokers are meant to be thin bands around the neck while collar seems to be used for any other neck-related attachment at any height of the neck. Aliases like belt choker to belt collar don't do much good in breaking this weird sort of distinction between the two. Particularly that it seems like bands of any size are relegated to choker while parts of a top or anything that goes around the neck is tagged with collar.
For example, a character I upload now, Lupa (Wuthering Waves), I've been tagging with metal collar for the shiny piece around her lower neck that I suppose in a way also serves as a halterneck (is it even one? its not a string or strap from the bodysuit that's keeping it together, considering it is backless). For a more general example, playboy bunny often features what we currently tag as detached collar + wing collar (the latter less so than the former). Though no one would refute post #9390947 being a choker (or maybe someone will?).
For other examples, we currently tag Nicole Demara with heart collar (see post #8594977 for ex). It's not really a band and it's part of the top (?) which the wiki for collar says it should only be for standalone collars, though is it appropriate to consider things like this and the aforementioned metal collar as collars? They're not exactly bands and they sit at the base of the neck. The wiki also only has pictured non-examples.