When you snorkel, you stay at the surface. You wear goggles that allow you to look down and see the underwater world very clearly. Scuba diving, on the other hand, takes you one step closer to all the wonders beneath the surface. When diving, you maneuver around rock formations, flora and fauna to see everything up close. The feeling you get when deep underwater is incomparable!
Snorkeling and scuba diving has another major difference, which is the way you breathe. To have fun while snorkeling, no complex equipment is used - a simple mask and a breathing tube do just fine. Scuba diving involves complex breathing apparatuses, with numerous tubes and a diving cylinder. Special training is required before you can dive underwater because you must understand the principles and usage of scuba equipment flawlessly, otherwise scuba diving can become an extremely dangerous activity.
Since scuba diving poses higher risk, you must get certified before you are allowed to dive by yourself. The most common track to become an independent scuba diver is obtaining a PADI Open Water Certification. There are numerous specializations and certifications you can obtain along the way, so you always have incentives to improve your diving skills. Snorkeling is less dangerous, so the rules are a lot more laid back. Very basic swimming skills, a mask with a tube, a diving suit and good mood are enough to snorkel.