Does anyone know the different types of legal corporation entities?
Corporate, meaning incorporated under the laws of your local state. Corporations can elect Subchapter S treatment under the revenue code. See form 2553 and applicable support. There are many different kinds of non-profits. Typically, when an organization is created they will file with the IRS noting what their purpose is. The IRS will send a determination letter, noting which part of the code they are exempt under. (Such as 501(c)(3). The instructions for form 990 might be a good place for you to start your research.