Not necessarily, see the below from http://www.census.gov/population/www/cps/cpsdef.html
Household. A household consists of all the people who occupy a housing unit. A house, an apartment or other group of rooms, or a single room, is regarded as a housing unit when it is occupied or intended for occupancy as separate living quarters; that is, when the occupants do not live and eat with any other persons in the structure and there is direct access from the outside or through a common hall.
A household includes the related family members and all the unrelated people, if any, such as lodgers, foster children, wards, or employees who share the housing unit. A person living alone in a housing unit, or a group of unrelated people sharing a housing unit such as partners or roomers, is also counted as a household. The count of households excludes group quarters. There are two major categories of households, "family" and "nonfamily". (See definitions of Family household and Nonfamily household).
Household, family, or subfamily, Size of. The term "size of household" includes all the people occupying a housing unit. "Size of family" includes the family householder and all other people in the living quarters who are related to the householder by birth, marriage, or adoption. "Size of related subfamily" includes the husband and wife or the lone parent and their never- married sons and daughters under 18 years of age. "Size of unrelated subfamily" includes the reference person and all other members related to the reference person. If a family has a related subfamily among its members, the size of the family includes the members of the related subfamily.
Household, nonfamily. A nonfamily household consists of a householder living alone (a one-person household) or where the householder shares the home exclusively with people to whom he/she is not related.