Pain is the feeling of hurt; a pane is a sheet of glass. They sound the same, so only the spelling and the context tell you which one is meant. Memory hook: a broken window pane can cause pain.
The core difference
Pain is suffering or discomfort, while a pane is a single sheet of glass in a window or door.
- pain — physical or emotional suffering: She felt a sharp pain in her lower back.
- pane — a sheet of glass in a window or door: A cricket ball shattered the pane in the front window.
How to tell them apart
Pain has an i, and so does the word ill: both are about feeling bad. A pane is a flat sheet of glass, and the final "e" can remind you of "window edge" or simply that a pane is part of a window.
The mix-up usually appears in "window pane", which is often mistyped as "window pain". If you mean glass, it is always pane. Pane can also mean a section of a computer window, as in the left-hand pane of an editor.