Eastern Caribbean Cruises
Most cruise ships sailing to the eastern Caribbean on 7-day itineraries embark from Florida. Ports of call on an Eastern Caribbean itinerary often include Nassau or an island in the Bahamas, St. Thomas, St. John (USVI), Puerto Rico, and perhaps St. Maarten/St. Martin. If you want less sailing (i.e. time at sea) and more shopping and opportunities to go to fantastic beaches, then an Eastern Caribbean itinerary might appeal more to you. The islands are relatively close together, smaller, and shore excursions tend to be more geared to beach or water activities.
Western Caribbean Cruises
Cruise ships sailing to the western Caribbean embark from Florida, New Orleans or Texas. Ports of call on a Western Caribbean itinerary often include Cozumel or Playa del Carmen, Mexico; Grand Cayman; Key West, FL; the Dominican Republic; Jamaica; Belize; Costa Rica; or Roatan. If you look at a Caribbean map, you will see that since the ports of call are further apart, more sailing is usually involved on a western Caribbean cruise. So you may have more time at sea and less time in port or on the beach. The ports of call in the western Caribbean are sometimes on the mainland (Mexico, Belize, Costa Rica) or at larger islands (Jamaica, Dominican Republic). Therefore, the shore excursion options are more varied. You can explore ancient Mayan ruins, hike the rain forests, or go snorkeling or SCUBA diving in some unforgettable locations.
If you are now thoroughly confused, that's okay! The Caribbean Sea is a cruise lover's heaven--blue seas, sunny beaches, and interesting ports of call. You will get all of these whichever direction you cruise. East and West are both great--and then there's the Southern Caribbean and Northern Caribbean, but that's for another day!