A stye (also referred to as a hordeolum) is a small, red, painful lump that grows from the base of your eyelash or under the eyelid. Most styes are cause by a bacterial infection. This may present a number of ways, appearing on the inner eyelid, or the outermost lid. Most forms of styes are caused by a condition called blepharitis (put a link to blepharitis—make it clickable).
A chalazion is a swollen bump, or a clogged oil gland that lines the eyelid margin. This is often the result of a stye, or hordeolum. Most chalazions do not have pain but can cause discomfort and impact vision.