Socially characters have several options in life. The difference between the types of groups available are different but crucial to knowing your place in life. A note to take in is that sometimes the names can be swapped about. "Order" could apply to either clan or guild. It's the nature of the group that makes it what it is.
This group is usually closely related by blood. You are born or married into it, though there are some clans that are connected through ritual. You cannot be part of more than one clan, typically, but there are exceptions. Women for instance are born into one clan, but are removed through marriage where men have the power of status, becoming part of her husband's clan instead. All in all, expulsion from a clan isn't usually very kind.
Work centered, one can be part of several guilds if they meet the requirements. Like a worker's union, guilds provide members with training and credibility for out in the world duties. These groups can stretch worldwide with bases in kingdoms, or be strictly kingdom oriented.
Very close to clans, these are family oriented as well, but only the esteemed reach this high order. People carrying status in the houses can be mere servants, as they still have stronger ties to them than you as a commoner.