Communities are open, online spaces with various rooms and tables that are crowd-sourced amongst it's members. For example, a startup community is likely to have rooms related to funding, and tables which summarize colletions of funding sources including grants, competitions, and investment groups. These tables can be added to by the entire community, and serves as a centralized space for the community to agregate knowledge.Groups
Groups are closed spaces which allow members of organizations, companies, universities, fellowships, or any other groups create a private collection of the information that is relevant to its members. An innovation fellowship group on Catalist could have rooms with lists of members and contact info, different tables with opportunities for projects, collaborations, job opportunties, or even events that are only to be shared with those inside of the groups.