We’re either friendly coworkers who invite other coworkers, or it’s like a meetup group of people who like something and want to do it together.
If we meet at a bar with coworkers, we can network with each other and thus later on not need to trifle with management when we need help with something. “Oh yeah, Jane built this device, lemme ask her what the polarity is supposed to be”.
Meetups with randos, we just vibe. Sometimes it’s at a bar, other times at a restaurant. We just vibe, figure out what other people’s passions and and get to know them.