Those names all refer to specific screen resolutions. For example, FHD refers to 1920x1080 pixels in a screen, with 1920 columns and 1080 rows. Each of these other refers to a different resolution. If you go this List of common resolutions - Wikipedia link, you can see some more exaples. On top of this, each one has another name frequently used that refers to the number if rows. For both 2560x1440 (QHD) and 3440x1440 (Ultra Wide QHD) can be referred to as 1440p for their given aspect ratio, 16:9 and 21:9 respectfully. The Aspect ratio is the ratio of the columns to rows of a resolution.
What is the difference between HD, UHD, QHD, WQHD+, etc., screen types? - Quora