It’s a symbiotic relationship. The European extremists say or do vile shit. The Muslim extremists recruit and say or do vile shit. The European extremists recruit and say or do vile shit and so on. And on it goes.
The difference is that one of these groups is way more powerful and can hide their vile shit in politics and media and among “lone wolf attacks”. Terrorism is almost always perpetrated by people without access to political/official power.
Typo? What did I miss?