Communist Revolutionary -- Someone with no money who uses violence to take money away from other people and control their lives.
Change Agent -- Someone with some money, probably sourced from foundations, who wants to use political and social forces to take money away from other people and control their lives, BUT they see themselves as good people.
Community Organizer -- Someone with government funding generally in the form of block grants, who wants to use violence and or political/social forces to take money away from other people and control their lives.
Back when I was self-employed I had a consulting gig with a large international environmental not for profit. This group had scored a large gift to do a certain task. They decided, after they had the money in hand, that they didn't want to do what they had promised. They had no intention of giving back the cash. This was my first experience in the NGO world of Community Organizers and Change Agents. For the life of me I still can't see difference between them and a highwayman; other than the cocktail parties.