Welcome to LCT, Jim.
The 3 major differences that I see between Radisson insurance and independently purchased travel insurance are:
1) Coverage of pre-existing conditions. Many independent travel insurance policies will cover pre-existing conditions IF you purchase your insurance within a specified time of booking your trip (usually 7 - 14 days) Radisson's insurance does not cover pre-existing conditions.
2) Coverage of other travel costs such as air and/or hotel. My understanding is that Radisson insurance only covers the cruise portion of your trip unless you purchase your air and hotel thru Radisson.
3) Coverage in case of the cruise line's bankruptcy.
If these items are of importance to you, you might want to consider purchasing independent coverage. Depending on your age, independent insurance may also be less expensive, while providing greater coverage levels. Here's a good site for checking and comparing travel insurance:
insurance comparisons Enjoy your trip.
