Anarchists - they are found all over the world.  You will find them wreaking havoc at the G-8 summit.  Technically a true anarchist represents no leader and has no true leader.  They have been around for centuries.

AntiFa - They are anti-fascists whose sole purpose is to go after and sometimes violently oppose white supremacists who call themselves fascists.  

Not quite sure how an article on climate change ended up in an antifa vs. anarchist debate.  At least you learned something.  You are welcome.  :-)