They are not the same thing, but in nuclear physics they are related in the following way:
You use the mathemtical technique of multiploe expansion to find out what the electromagnetic field of your nucleus looks like, which, I guess, is what you mean by multipole fields although I have not heard that term before.
You then use those properties you have found to compute specific aspects of the electromagnetic radiation that is emitted/absorbed by the nucleus or between states of the nucleus. This radiation is called multipole radiation and it is a very deep, interesting and complex field.