A spouse is the person to whom you are lawfully married as evidenced by a legally certified document of marriage.
Adding a Spouse
Establishing a Common-Law Relationship
A common-law partner is defined as a person of the opposite or same sex who is living in your household and who has been reasonably established to have been resident with you for a period of at least one year and who has been maintained and publicly represented by you as your partner in a marriage-like relationship.
Adding a Common-Law Partner