A style guide defines how elements should look – it sets colors, fonts, logos. A design system goes a step further: it's a collection of reusable components and clear standards that serves as the single source of truth for both designers and developers.
In other words, a design system isn't just rules, but also tools – ready-made building blocks (in the form of design components in Figma and corresponding code components) that your teams can quickly and consistently use to build new features and products.
For a company planning digital ecosystem development (e.g., exchange, wallet, mobile app, marketing site), a design system isn't a design project – it's a strategic investment in foundations for scalable growth.