Difference from range rover and Land Rover?

Land Rover Motor Company is the main automotive company. The Range Rover (and now the Range Rover Sport) are simply models under the Land Rover Marque. Land Rover cars including the LR2 (Freelander 2) and the LR3 (Discovery 3) are maked with "Land Rover" simply because they are different models. In short, Land Rover is the company and Range Rover is a specific model. The difference is just in the various models of cars.