How and what curtains to hang in windows with different sizes?

I would either use long curtain panels on both or leave the high window un-curtained if privacy is not an issue. Using two different panel lengths is not the best length in one room if you can avoid it.

I would hang the regular window drapes close to the ceiling. If you need to curtain the high window, I would hang them close to the ceiling matching the other windows with length so that when the curtains are closed they would look nice together.

I agree with Debi, you could use custom shade in the same fabric as the long curtain. Just buy one of those roller shades and then cut and cover it with the curtain fabric. You could also apply a decorative window film in the colors of the curtain to the short window.

Some also make 2-part cafe curtains for both windows to hide the assymetry of the short one covering the wall space where the window is short.

Use the same size drapery panels/curtains on both windows, making the top rod on both windows the same height. If the drapes were closed, the windows would look to be the same size.

Here's a link for some ideas about your windows. https://homeguides.sfgate.com/decorating-ideas-make-windows-look-longer-31990.html

Hi Tina, are they both at the same height up top? You could just use the same curtain length on both.