I think there's crossover but I don't think those two groups are motivated by the same thing.
My observation is that far-right activists tend to feel that they're being deliberately stabbed in the back by the powers that be, rather than seeing themselves as collateral damage. They're also significantly more likely to be paranoid, and they perceive their targets as you would an invading army.
Far-left activism isn't like that. They don't perceive The Man as sadistic, they perceive him as disinterested. "Nobody cares about global warming" vs. "they're deliberately raising the temperature of the earth to hurt me." I also get the vibe far-left activists often engage in activism for fun. It's an exciting mission to break into the farm with your friends. They almost always do it in groups, whereas you're more likely to see jilted right-wingers plan solo attacks like this guy.
(I'm not trying to paint the far-left as better here. I think they're often quite dishonest about their motivations, whereas the far-right is extremely up-front, pied piper gurus aside. I think that's one of the reasons paranoid schizophrenics gravitate more toward the far right, although it helps that their narratives are more about conspiratorial persecution.)
The demographic distributions are also different. Almost all far-right activists are male, whereas vegan & climate activists are mixed.