The quick answer can be found in the two different names. Snoring is irritating to others but not life threatening. Obstructive Sleep Apnea, however, kills thousands of people each year.
If you read the packaging on a snore guard or similar product, you will NOT find any mention of sleep apnea at all. The FDA has approved snore guards to treat snoring but definitely not Obstructive Sleep Apnea.
An Oral Sleep Apnea Appliance treats Obstructive Sleep Apnea AND snoring and, as a special added bonus, can save your life.