Both these series contain the "goddess" theme, becoming one of the major themes. There is envy, jealousy, and later love present in both series as the episodes progresses.
Both series contain supernatural elements as well as mixed in comedy and misunderstandings. Also, expect drama and the "little sister" annoyance that are present who tries to help the main protagonist through his problems. (namely involving love)
Despite the lack of superficial similarities in the plot or setting, these two shows are both light hearted and enjoyable romantic comedies. For people who enjoyed Mamoru-kun and are looking for another slightly overlooked, fun romantic comedy, I think Kamisama Kazoku fits the bill perfectly.