I think this is the best answer. But actually there's at least 4 levels.

As said, Trash is actively in your way and blocks useful items until you deal with it. It sucks.

Scrap takes inventory space but you can refine it or sell it for something useful. So it's almost a currency, just with extra steps.

Junk is filler, you may have to scroll past it but it's just weightless fluff that only occupies space visually. You don't have to deal with it in a meaningful way.

And then Trinkets are all the little trophies and audio logs that get their own special screen you can just 100% ignore if you want.