What are those curtains that aren't curtains called?

I’ve already seen with the name stationary curtains and fixed curtains, some call faux curtains but apparently that is the name of a specific model as well

How and why are they not curtains?

I'd probably just call these drapes

I would call this a “valance.”

I think you are talking about window shades. They go inside the window frame and are plain and open white colored. The most common ones Americans have are the horizontal slats that can be angles with on rope pull and pulled up with a second rope.

I would go with 'drapes'. Drapes can also be fabric curtains around a window, but 'decorative drapes' sounds less wrong than 'decorative curtains'

I'm not a native speaker, but I feel like "draperies" would describe this type of decoration.

Those are curtains on rails. They are regular functioning curtains that have small rolling pieces that run on the small rails attached to the corner of the wall/ceiling. I don’t find them really being used in North America, but I’ve seen them in other regions. They might be a posh exclusive thing in North America and I just don’t have the means to have them here

Fake curtains perhaps? Notice how they just hang there, their "pole" (?) is too short to actually cover anything. They're only there to soften the space. Fake curtains, perhaps?

That's odd, curtains like that aren't common. But they're still called curtains, they just haven't been hung so that they can properly do their job. And "curtain rod" is the name for the pole that curtains hang on.

I’ve already seen with the name stationary curtains and fixed curtains, some call faux curtains but apparently that is the name of a specific model as well

I would call those blinds.

Drapes maybe ?

Shades

"window treatments" though that's kind of a catch all term

Or blinds

Or blinds for the window