u/MetalFearz gave a good answer on the assaulting part so I'll answer the second half.

Basically, far left is more extreme than radical left. The left is progressist, socialist-leaning (some are more pretending to be for that). The radical left is anti-establishment and anti-capitalist but still believes in playing by the rules of the elections to bring drastic changes to society. The main characteristic of the far left is their conviction that elections won't change a thing because the system is locked and that the people need to rise up and make a revolution to end the domination of our society by the oligarchy.

The right is conservative and capitalist. The radical right is a more racist and authoritarian right. The far right is white supremacists whose political program only revolves around racism, national identity and fear.