Final answer:
Polygamy is the marriage of more than two adults, and polygyny is a form of polygamy where one man is married to multiple women, often bringing economic and social benefits to the family and society.
Step-by-step explanation:
The fundamental difference between polygamy and polygyny lies in the number and gender of the partners involved. Polygamy is the formally sanctioned union of more than two adults at the same time, which can lead to several forms of marriage including polygyny and polyandry. Polygyny is a specific form of polygamy where one man is married to more than one woman at the same time. This practice is significantly more common than polyandry, which involves one woman married to multiple men and is prevalent in cultures and societies across northern Africa and east Asia. Polygyny is often associated with social status, economic benefits, and strong political alliances; it maximizes the family labor force and the shared resources available for family members, creating extensive kinship connections within the society.