Very often, people confuse a chalazion with a stye. A stye is very painful. It is a red lump located on your eyelid’s edge due to an infected eyelash root. It usually swells, sometimes affecting the entire eyelid. On the other hand, a chalazion is a painless bump. It can develop within the upper or lower eyelid, although the upper is more frequent. It is a bump that develops farther back on the eyelid than a stye.
The main differences are that a chalazion tends to be painless, whereas styes are tender, redder, and display more signs of inflammation overall.