The biggest difference, of course, would be that a public serving radio service is owned and financed by the public. In other words, it is paid by us through licensing fees. A commercial radio service (privately owned) is financed by themselves through advertisements; the public is not paying the station, the advertisers are. Think of BBC Radio vs HEART. As a result, they can broadcast much more than a public broadcaster.
There are also different reasons for broadcasting. Public stations are there to “educate, inform and entertain” the audience who pay their fees. Commercially owned stations have much more freedom on what they can broadcast, within reason, but they also need to draw in big audiences to keep their funding through advertisements.
Another difference is that commercial stations like to play music by musicians that are nationally recognised so they can get the ratings they need. Public stations have more freedom in this area as they do not have the same pressures.
Who controls the rules for broadcasting and how?
The office of Communications, or Ofcom, is the UK’s government-approved regulator for broadcasting. It exists to represent the interests of citizens and consumers, and protects them from harmful or offensive media. It does this by licensing all UK television and radio services. Broadcasters must comply with the terms of their license agreements; if they do not, their license is revoked. There is a broadcasting Code published by Ofcom which requires content inappropriate for children not be broadcast between the hours of 5:30 a.m. and 9:00 p.m.