My opinion: Clans, Guilds and Clubs are all different ways to describe different sorts of groups of people that play games together. Clans or normally focused on fighting as a team (usually in FPS shooters). Guilds are usually in MMOs to help build a strong alliance between members. Clubs are something unique to Blockland, and they are a group of people that enjoy building and hanging out together.
I created the first self-proclaimed "Building Club": the Blockland Builder's Club (BLBC for short). Yes, we have a dedicated server up sometimes. Yes, we will have our own website, yes we have places for us to discuss together (not our own forums though). We're not oppressive though. We offer free-building areas on our servers for other people who aren't in the Club or good friends of the club to build in. We don't have tags on our names, we don't think we need to tout that as a piece of our resume.
Why don't we let just ANYONE into the BLBC? Because we like to build with great builders, with mature people, and with people that have personalities that blend well with the group. If someone comes and types all caps, "OMG THIS SERVER ROX! I WANT TO JOIN YOU PLZ!!" why should I be obligated to let them in? I don't know them, they are obviously very noobish if they don't use good grammar, and it also looks like they aren't used to hanging around good builds. Would you like to babysit a bunch of people in your group? I like to just have a server up, give every BLBC member the admin pass, and just let it evolve and take shape on its own. I can't do this if I let everyone be in the club.