Total eclipses completely block out the body that is being eclipsed, such as the Sun. Annular (which comes from the Latin "annulus," or "ring) eclipses leave a border of that body visible. For example, in an annular solar eclipse, the moon appears to have a "ring of fire" around it.
Total solar eclipses occur if the Moon is relatively close to the Earth and annular eclipses if the Moon is further away. Try this with your thumb and a low-powered flashlight or lightbulb. (Always be careful to protect your eyes - don't look directly at the sun!)