Per the Community Membership page, Special Interest Groups (SIGs) are:

Users, Contributors, Partners, and organizations that come together to address a specified set of use cases – usually industry- or vertical-specific – in a specified location and language.

Open Horizon SIGs are proposed by sponsoring organization and Partners, self-forming, and chartered by approving vote of the TSC.  SIGs are designed to:

• identify use cases within an industry or vertical,
• develop end-to-end reference solutions, and
• promote the solutions, use cases, and the group itself. 

By way of comparison and contrast, LF Edge's End User Solutions Groups (EUSGs) have a goal to:

• gather user requirements through cross-project discussion with end users and
• generate demos, white papers, and messaging in order to
• prioritize project features and inform project roadmaps.

Open Horizon's SIGs include:

• China Manufacturing SIG - Los (Liang Wang)
• Smart Agriculture SIG - Bill Rowley
• In collaboration with EdgeX Foundry and SDO projects: Open Retail Reference Architecture (ORRA) - Arnaud Le Hors and Jesús Centeno