In the beginning, you usually need a leader.
This leader needs connections, expertise, or charisma to get a community started.
They need to convince a small group they can create a separate, better, future within their field. They need to challenge conventional wisdom, endure criticism, and stand firm against attacks from inside and outside the community.
Leaders are also good in times of need. If the community hasn’t gotten off the ground, has faltered, or if you’re enduring a crisis, you need a community leader.
Leaders decide what members can and can’t talk about. They decide what the community concept does and doesn’t include. Leaders don’t build a community around what members want, they build a community around what members need. They're focused on the future.
Leaders remove the people who aren’t a good fit for that future.
Existing communities need a community manager. They need people who work in the background to keep as many members as engaged as possible. They need someone to remove the bad stuff, highlight the good stuff, create content, and ensure the community personifies its topic.
Everyone knows who the leader, most members might not know who the community manager is.
Leaders also tend to have major weaknesses (these weaknesses might drive them to success). Their strengths outweigh their weaknesses. Community managers tend to be more restrained in strengths and weaknesses.