Snoring is of several types, mild snoring, severe snoring and sleep apnea. Snoring generally makes a loud and unpleasant and discomforting sound. Generally a person sleeping alone doesn't come to know that he/she is suffering from snoring.
Snoring is vibrations of soft tissues in throat like uvula, soft palate, adenoids and tonsils. Sleep apnea is the severest form of snoring in which the person's breathing gets blocked, so the person wakes up frequently to breathe. However, the person doesn't remember waking up.