What is the difference between thicknet and thinnet cables?

Thicknet or 10BASE5 is able to run 500 meters. Thinnet or 10BASE2 is able to run 185 meters. Thinnet cable has a smaller diameter (it is thinner cable) and is more flexible and so easier to work with than thicknet. In the old days you would run a thicknet cable in the ceiling as your network backbone and use vampire taps to attach thinnet cables ("drop cables") that would drop down into rooms in the office where they would connect to hubs. This setup is caled a bus topology. The problem was if that if any piece wasn't properly terminated or is any one cable broke then the whole network went down and you'd have to run around trying to locate the break.