Halos are bright circles that appear to surround a source of light, such as oncoming car headlights. Glare is light that enters your eye but doesn’t help you see better. Rather, it interferes with your vision.
Glare can be:
Uncomfortable. When you’re trying to see in the presence of a too-bright light, you may squint and try to look away from the light. Your eyes may become teary.
Disabling. Glare can sometimes impair your vision. Light is scattered within the eye and reduces the contrast of images. The loss of contrast is often worse with disabling glare in dim lighting as opposed to bright environments.