I bought my textbooks at the co-op.
When I was a university student, I bought textbooks at the co-op.
We use the co-op's home delivery service every week.
As soon as I enrolled, I joined the co-op.
She's a co-op member, so she gets a discount.
I bought a laptop cheaply at the university co-op.
組合 is a broad word for any union or association (labor unions, trade groups, etc.), whereas 生協 refers specifically to a consumer cooperative.
生協 is the common Japanese term for a consumer cooperative, while コープ is the katakana loanword often used as a brand name for the same kind of organization.
農協 is the abbreviation for an agricultural cooperative (for farmers), while 生協 is the abbreviation for a consumer cooperative (for daily goods and food).
Used when counting 生協 (co-op) as an organization or corporate entity.
An abbreviation of 生活協同組合, formed from 生 in 生活 and 協 in 協同.