Relationships and households in 360Members often work hand in hand, but they are different ideas. A household is a collection of people that live together. These people do not necessarily have to be related, for example, a friend of the family may be temporarily staying in the same household as a family, but would not be considered a family member, but he would be considered a member of that household.
Family relationships however, don't require people to be in the same household. For example, if a child moves out of their parents household, he is still his parents son, and can be denoted as such in 360Members, but he can be in a different household. This would appear in 360Members on the child's person record with his parents still being listed as his parents, and on the parents, the child being listed as their son, but if you look at the household records, the child would be listed in his own household, separate from the parents.
The simplest way to think about this is:
1. Being in the same household means you share an address and are all listed as members of that household
2. A family relationship indicates a familial relationship with another person, but not necessarily being in the same household.