The difference is in size and ride. Our 12 passenger Zodiac is smaller and faster, almost like a roller coaster ride (depending on the weather). It is very popular and exhilarating but there are a few restrictions. If you have back or neck problems, pregnant, or under 3 years old, it is not recommended. On board our 25 passenger Research Vessel, there is the captain, bilingual guide and 2 researchers. This boat is more family-friendly with no restrictions.There is also a washroom on board and more room to move around, whereas in the zodiac you are required to stay seated for most of the trip.