Yep different. The Frequencies are the same, 9Khz spacing for AM (MW) and 100Khz for FM. However the UK units will have other little things like 'auto traffic', station ID. and will freqency hop, say you tune in BBC2 it will look for the strongest BBC2 frequency. It will more than likely have long wave as well.
The secure thing will probably be just the radio security code needs entering.