Both are evil. One isn't worse than the other. And, they aren't even really the same. But they do have the same origin; a poisonous idea and belief.
Radical Islam is a poison, which infects once the person is angry as his/her life and feels someone else is not only to be blamed, but should be punished with death. Just as you have Radical Islam, you have radical/fundamental Christianity or even an extreme political view (again, a poisonous idea you've taken up because you are pissed off at something or someone).
Nazis are fascists - fascists demand you live life (and even look a certain way) or else.
There are no peaceful fascists. But, there are peaceful Muslims.