Let me not agree with your comment. They are not two groups. Islam terror grows in the soil of Islam, not other soil. And Muslims are followers of Islam. Do you mind to count the  radical Islamic organizations and groups in the world - dozens (Hezbolla, Muslim Brotherhood, Boko Haram, Al Qaida, ISIS, HAMAS, As-Shaab, Al-Nusra, Takiban, and so on). Their support in Muslim world is huge, otherwise they would not survive.