The difference between a cyclone and a tornado is much more than whether they just occur over land or water. While this is one of their differences, you have to look farther into what makes them grow into the weather disasters and phenomenon that they can become, in order to truly understand what makes them different.
It is true that a tornado is a land event, while cyclones are created and fester over the oceans. A tornado, even the largest ones, is relatively small when compared to the cyclone. You might have a tornado that stretches for several miles, but a cyclone can stretch for several hundred miles. The atmosphere just above a land mass will encourage the development of a tornado, while that same factor will sap the life from a cyclone, and, in many cases, eventually help to destroy it.
The time frame from the birth of a tornado until it dies out, is generally measured in minutes. The time frame from the birth to the death of a cyclone, is measured in hours and days.
There is no way to say which of the two is more destructive. It mostly has to do with the area of development, and what might be in its path. However, the tornado delivers devastation to buildings, infrastructure, and people, in a very centralized location in relation to its development. A cyclone can cause widespread damage to any number of regions within its path. The type of damage is also different. The tornado provides fierce, intense damage, while the damage of a cyclone is caused by continuous battering, and drawn out exposure.
Outside of being potentially deadly weather phenomenons, the greatest link between a tornado and the cyclone is found after the cyclone reaches land. The atmospheric instability, the ambient and atmospheric temperatures, and the weather conditions that surround the cyclone, can make a fantastic recipe for the development of tornados. Alternatively, the tornado does not provide the right conditions to develop a cyclone.
