Bylaws set forth the structure of the organization and create a governing board with final authority for the organization. The Code of Regulations is similar to the constitution for an unincorporated organization. The document sets forth all rules and regulations for the governing of the organization, duties of officers and trustees, rights of members and fees or dues for members. Many organizations now have just one document, usually called "the bylaws" that incorporate all the information formerly contained in the separate documents. 

A sample of nonprofit bylaws for organizations with and without members can be downloaded here.