DAB digital radio is a terrestrial-based system, which means the services are broadcast on a number of multiplexes across the country with capacity for a certain number of services. These multiplexes are broadcast in different areas/regions via many transmitters across the UK. For DAB, the selection of stations you receive will depend on where you live. DAB radio is free to listen to.
Satellite radio is a digital radio signal that is broadcast by a communications satellite, which tends to cover a wider geographical range than terrestrial radio signals. However this service is often subscription based and consumers have to pay to listen to it. In areas with a relatively high population density, it is easier and less expensive to reach the bulk of the population with terrestrial broadcasts. Thus in the UK and elsewhere in the world, we have focused on DAB rather than satellite radio.