The four different types of coral reefs are fringing reefs, barrier reefs, atolls, and patch reefs.
Fringing reefs grow near tropical coastlines around islands and continents and are the most common type of reef formations. They are similar to barrier reefs except they lack a wide deep channel between the reef and shore.
Barrier reefs run parallel to the coastline and are separated by deeper, wider lagoons usually on the edges of the continental shelves. At their shallowest point they can reach the water's surface forming a "barrier". When seen from the air they will look like a white line on the ocean surface. The Great Barrier Reef in Australia is the largest and most famous barrier reef in the world. The second largest lesser know barrier reef is the Mesoamerican reef. This reef runs from the tip of the Yuctan Peninsula to the Bay of Honduras.
Atolls are ring like reefs of coral that create a protected or partially protected lagoon. They are usually not located close to the coastline and are in the middle of the sea. More Atolls are found in the Pacific than in the Atlantic. The only Atolls in the Atlantic are found off of Belize and the Turks and Caicos island groups. Belize has several Atolls that have been protected where you can find many invertebrates and fish growing very large do to this protection.
Patch reefs are coral reef formations that have developed independently of main reef systems. They grow between the shore and barrier reefs in shallow water where substrate permits the growth of new coral colonies.