The name of the gray/light gray stained glass/glass panes does not match their ID.

I wanted to make sure I remember the ID of gray stained glass panes for a project I am working on, so I searched "gray stained glass pane" in the creative menu, and nothing showed up. So I searched "grey stained glass pane" (grey with an "E") and it showed up. I checked the ID, and it was "minecraft:gray_stained_glass_pane" (with an "A"). It is confusing...